Cannot add constant power that centres on cut, even though I have handles

[Fin DePencier]

Hey guys, 

I've been having this problem since there was an Adobe update a few months ago. Why can't I add a constant power inbetween my audio tracks? Both the clips have handles, there is quite a bit of space on either side, but Premiere is only allowing me to add the effect at the start of the cut. 

One hint seems to be that when I drag one of the clips forward a bit, Premiere allows me to add a constant power at the end of the clip that centres on cut. But then I am subsequently disallowed from adding a centre on cut at the beginning of the clip. 

These are clips with a lot of extra audio (handles) to work with on either side, so this doesn't make any sense. Someone please help me!

[Ann Bens]

What is the default duration of the transition.

How many handles do both clips have.

Post screenshot of transition in the Effect Controls.

[Richard M Knight]

Have you edited the audio with audio time units selected? You might have a subframe gap.

[Richard van den Boogaard]

This seems a likely scenario. Was @Richard M Knight's advice a solution to your problem, @Fin DePencier?

[Fin DePencier]

So I looked up this problem elsewhere on the forum, and someone said I should delete my media cache, which I did. That seemed to fix the problem but now I'm having it again. So please explain the sub frame gap, I do edit with audio time units selected sometimes, because I want to be as precise as possible. 

[Richard M Knight]

If you cut out a few milliseconds of audio leaving a short gap when in Audio Time Units, when you switch back to 'video' frames it might look like the audio joined where there is, in fact, the short gap.