We’d like to apologize, but something slipped through the cracks when we validated Shotgun Desktop 1.6.1 with older versions of the tk-desktop engine. We spent of lot of time making sure we reported incompatibilities when trying to load a version of tk-desktop that wasn’t Python 3 compatible in the Python 3 mode, but have been blindsided by Python 2 mode not being backwards compatible with older engines.
The gist of it is that because we are now packaging PySide2 instead of PySide, the PySide2 API doesn’t quite behave the same (QAction’s trigger signals being the biggest offender here) and it has introduced some bugs for users who have locked their site configuration’s tk-desktop engine to v2.4.12 and lower.
To avoid any future confusion with our users, we’ve released yesterday an update for Shotgun Desktop’s startup code that takes into account the tk-desktop version, the Shotgun Desktop version and reports any incompatibilities. It should auto download to your computer next time you launch Shotgun Desktop.
The pop-up will provide an explanation of the issue and suggest two ways to fix the problem.
Hopefully this will clear any confusion around this issue.