So there are mechanical constraints on matching bulbs to fixtures and we don't know and maybe cannot know what they are in advance.
Incandescent bulbs somehow seemed to do a much better job of not having these problems.
Maybe me not having this kind of problem was the exception and not the rule.
So back to the bricks and mortar store and this time you try each energy saving candidate bulb in several of their fixtures. The problem is you'd need to check with a multimeter if the bulb is making contact and I doubt the store clerks would put up with that.
A cardboard profile of the bulb might also work and it's not difficult to make one.