When both server and client are version 1.0.6 (1.0.6-r15847-2) on ubuntu 14.04 64 bit, clipboard, enabled as bidirectional, works normally.
However, when the server is upgraded to 1.0.7 (1.0.7-r16697-1), while the client remains the same, the clipboard does not work. No error message was found in the log. The only clipboard relevant flag is on the server side: XPRA_CLIPBOARD_LIMIT=30.
This sounds like r16687 might be causing problems again..
If that was the case, you should be seeing this message in the log:
Warning: sanitizing invalid gtk selection type atom %#x
Will try it in a VM.
The backport was incomplete and broke things, r16757 fixes that.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/1625