Yeah, I have this issue too, it is really annoying.
As mentioned above I recommend to use PopClip with Auto-appear turned off by an exclude rule in any apps that exhibit a problem like this. Use the keyboard shortcut to activate PopClip when needed.
Alternatively, train yourself to hold down â while selecting the text, which inhibits PopClip.
This has been a huge source of frustration for me the past few months, and Iâve finally pinpointed PopClip as the culprit.
I use PopClip on a MacBook Pro (client) that I access from a Mac Studio (host) via Apple Screen Sharing. Itâs typically a seamless experience. Universal Clipboard is enabled and the Mac Studio runs Paste, so every copy action on either the client or host adds an item to Paste on the Mac Studio. For months, I havenât been able to figure out why simply selecting text with my mouse in some, but not all applications on the client machine overwrites my current clipboard content. Hereâs what happens:
- I copy something that I intend to paste over existing text on the client machine, and that target may be in VS Code, Cursor, Excel, or several online SaaS apps.
- The moment I select the text I intend to replace, my clipboard content is overwritten with the selection and I just end up pasting the existing text over itself. If it werenât for Paste making noise on my host machine, I wouldnât have realized that the copy action is triggered by copy-on-select on the client machine.
It makes copy/paste the most tedious experience; especially because how inconsistent the behavior is. This doesnât happen in Cocoa apps like Notes, but does happen in Excel, VS Code, Cursor, and browser web apps. And even in Cursor, it only happens when selecting text in the document editor; it doesnât happen when selecting text in the agent sidebar.
With Geminiâs help, I was able to narrow this down to PopClip. And, the explanation it gave is in line with what Iâve read in this thread - PopClip is copying-on-select under certain conditions so it can resolve which extensions to offer in the popup. But what isnât happening is PopClip reverting the clipboard content back to its original state. If I understand correctly, hereâs whatâs happening:
- I select text in an app that PopClip canât recognize whatâs selected via the accessiblity API, so it copies the selection to the clipboard to evaluate it.
- That copy action is picked up by Universal Clipboard.
- UC overwrites the clipboard on the host machine which then triggers Paste to record a new item in its clipboard history.
What I donât understand is, why doesnât this happen on my Mac Studio, where I also have PopClip installed, along with the same âproblem apps,â but a select action does not overwrite the clipboard content? Universal Clipboard is bi-directional, so why would these selection/evaluation actions affect UC on one machine but not the other? I do not believe that Paste is a factor because the behavior happens on the client machine regardless of whether Paste is running on the host or not; and the behavior never happens on the host machine regardless of whether Paste is running or not. That would suggest the problem is with Universal Clipboard, but why in only one direction? I thought maybe it could be related to the new clipboard history in Spotlight, but thatâs disabled on both machines.
Iâve loved PopClip for years and am desperate to keep using it, but if the only option is to manually trigger it via keyboard shortcuts, that diminishes its value and ease-of-use pretty significantly.
I am using 2025.9.2 (5155) Standalone version on both machines.
PopClip does always attempt to restore the PopClip board back to its original state.
However, there is a mysterious glitch â which I am unsure whether it is a PopClip bug or a macOS bug â which has occasionally plagued some users for years. In this mysterious state, PopClipâs attempts to restore the original fail.
It seems that this can be affected by the presence of certain clipboard managers or other tools which modify the clipboard; but not necessarily.
Frustratingly, I have never been able to recreate the problem myself in order to debug it or narrow down the exact conditions or tool-combo that create this issue.
I have gone over every line of code regarding restoring the clipboard content multiple times, and I have not found any reason why it would fail. And most of the time, for most people, it works fine. So, itâs very frustrating!
As you have mentioned, the operation of PopClip depends on this use of the clipboard in applications that donât support the accessibility API. Currently, my only viable recommendation is to turn off automatic appearing when it causes an issue, and use a keyboard shortcut.
I suppose there is a middle ground where we only have automatic appearing for applications that support the Accessibility API and not for ones that require the pasteboard swizzle. Thatâs not an option in PopClip currently, but it could be. But I think this could be even more frustrating, because then it would appear some of the time and not others, which might be worse that not appearing at all.
Iâve added to my to-do list to revisit this issue, maybe look at some kind retry mechanism to try to force the pasteboard restore if the current first attempt failsâŚ
Itâs just that itâs very hard to develop such a thing without the test conditions to try it against.
If anyone has a reliable way for me to, from a fresh install of macOS, get to the ânon-restoringâ state, would be very interested.
I suppose, as an intermediate step, I could work on âdetectingâ the problem. If detection is possible, it put up some kind of warning: âPopClip failed to restore the pasteboard! 
â So at least users know why their pasteboard is messed up!