Shift also doesn't constrain movements to horizontal/vertical/45° angles. Why would such a fundamental function change?
It did not change. If it isn't working for you the problem is in your system configuration someplace.
When I hold shift down to constrain shapes, it doesn't work for me either. As easy as it is to give us feedback of "it's in your system configuration", I've checked, and everything seems to be correct. If you think that's the problem, can you provide screenshots of any preferences we need to have checked or unchecked to solve this problem? Thanks in advance!