Welcome to the forum NeoDLL and that for reporting this issue.
I investigated this issue a bit.
According to Microsoft and some other sources, this happens when an app is locking the Clipboard while QCE tries to capture the Clipboard change to add it to the Clipboard History. Could it be that the Cisco app is playing the the Clipboard content when you paste a phone number in it? I'll have to investigate to see how I could trap this error before showing the error message.
Can you systematically replicate this issue? If yes, it could help if you test the next QCE release to see if this persist.
Also, could you try increasing the delay value in the QCE ini file to 1000 milliseconds (instead of the default 500) to see if this has an impact?
[History]
HistorySyncDelay=1000