Audio waveform disappears every time I make a cut in clip

I have two iMac

Number 1. (Retina 4k, 21.5inch, 2019), Processor 3GHz 6 Core Intel Core I5 Memory 8GB 2667 MHz DDR4.

Number 2. (Retina 5k, 27inch, 2019), Processor 3GHz 6 Core Intel Core I5 Memory 8GB 2667 MHz DDR4.

My FCP is 10.6.

I have been using both iMacs for two years to edit my videos in FCP. I edited over 500 videos with both IMacs, and the workflow was always great. Of course, the waveform would disappear every now and then for about 2 or 3 seconds but not all the time, and I was always able to work on each project with no problems.

Since last week, I have been having problems with the waveform of the audio file disappearing for 15 seconds every time I cut the clip.

I import the video and audio files as usual. Once everything is in place and ready to be edited (rendering, transcoding, analyzing, thumbnail and waveforms, etc., ALL DONE), the audio waves disappear as soon as I start cutting the clips.

For example:

1. Both video and audio are perfectly in sync, and the waveform is showing. The video plays smoothly.
2. I cut, and the waveform disappears for about 15 seconds.
3. The waveform appears again.
4. I make another cut, and the waveform disappears again for another 15 seconds.

I edit the file from the IMac (no external drive) and I always have around 700GB free on my disk.

I noticed that there is a new update (Mac OS Monterey). Will this update fix this problem?

Can you guys advise? Are you also experiencing this type of issue?

Marco.