Hi!
This happens a lot since the update, in both Chrome and Firefox. It is not 100% consistent, so sometimes it works normally:
When I place a content block with simple content in one section, and another one in the second, sometimes I cannot switch between them by clicking one and the other respectively.
For example if I am in content block 1, I have to first click something else and only then I can move into content block 2.
I have successfully reproduced the issue (Firefox/Chrome) in a clean Sandbox install.
There was another issue which I wasn’t able to reproduce: Same thing happened on switching between two Classic Feature boxes.
Thanks!