I wasn’t sure whether or not this is the right place to post this. Since this is all core, I figured I’d put it here.
I’ve created a block from a menu and put it in the sidebar2. It appears fine on basic pages, but disappears whenever the user is on any page generated by a view. I tested a few other blocks and found that custom blocks also disappear on Views pages. The order doesn’t seem to matter. The only block type I’ve tried that seems to appear on every page is a List (Views) block.
There are no restrictions on the blocks with respect to pages, content types or roles.
Anybody have an idea why this would happen? I saw similar posts for 6.x and 7.x, but I haven’t seen anything helpful related to this issue in 8.x.