I know this is an older thread, but I have a bit more info as well as some help on the matter that may help others looking for the same problem.
If you’re running windows, you can view all previous clipboard entries by pressing Win+V and manually select a previous copy to paste instead, with the most recent at the top.
By default, Ctrl+V or Right Click+Paste will make Windows attempt to paste the topmost entry on the clipboard, matching usual expected behavior.
There’s an exception to this rule: Selecting one of those previous entries manually will instead cause all future paste operations to use the most recently selected entry.
As for the bug, copying an AssetID from Studio will in fact copy the asset to the clipboard but also copy a blank/null entry to the clipboard right after, giving you this for example:
This seems to mostly happen if using the “copy AssetID” button that appears when you successfully export something to Roblox. So, if you need to paste that AssetID to several places, you only need to manually select it once as explained above, then you can Ctrl+V
it to any other future locations.
As Windows pastes the topmost entry whenever you press Ctrl+V, it will paste the blank entry there, causing it to appear to fail. However, your copied AssetID is still technically there, but there’s just an extra step to access and paste it properly.
You can also press the three dotted lines next to each entry to have the option to delete the entry. As for the exception, Ctrl+V will instead paste the last manually selected entry regardless of what is at the top until the next time you copy something. So if you need to paste that AssetID to several places, you only need to manually select it once, then you can Ctrl+V it to any other future locations.
Do note that just deleting the blank entry will not automatically set the “active” paste to the new top entry, as Windows is still trying to paste something that no longer exists. You have to manually select a clipboard entry at least once in order to have future Ctrl+V presses paste the most recent one.
For the Studio developer staff, I hope this gives a bit more insight into a potential fix.