This happens on my Elite smart rollers and will happen if I use either my stages crank or the built in powers meter in the rollers.
The numbers are just an example of what I experience.
When doing a plan, I have a warm up section, then the interval starts eg 80w up to 200w.
The trainer/crank reads 200 for a few seconds, then The software makes the rollers easier and it slowly drops down to 140-150w,
Then the software tries to compensate and it jumps up to 230-240w,
Then back down, then back up and it keeps doing this I until it equalises itself.
This could take 25-30 seconds and then my interval is over by the time it figures itself out.
For the rest/break, it drops back down to 80w, then down to 50w, then up to 120w until it can equalise again.