What version of Premiere Elements and what computer operating system is it running?
Where is the Timeline Indicator?
If you have the Timeline Indicator on the first audio clip and the first audio clip selected, the Add Remove Keyframe diamond will be active.
If you have the Timeline Indicator on the second audio clip and the second audio clip selected, the Add Remove Keyframe diamond will be active.
Please explore that suggestion to determine if that is what is at the core of your observation.
That was it! I always had clip selected but did not always have Timeline Indicator on clip! Thank you!
Thanks for the reply and the great news that the suggestions worked for you.
Thanks for pointing out this issue. It is one in which the Timeline Indicator position often goes overlooked. For me too.