I was about to shoot a  - relatively rare - sunset today when the leftmost light on the RC Pro turned blinking blue and the preflight check reported "RC Calibration" error.I switched the a/c off, as prescribed, then went through the motions of calibrating.
The error came back. And again. And again. Restart several times. All in all, probably wasted 10 minutes, losing most of the light, until after yet another attempts the light changed to solid green and I could take off.
Not sure what caused it. I noticed the left joystick could not reach 100% in some directions, no matter how many times I tried, yet calibration somehow succeeded eventually.
The a/c flew solid, with no drift I could notice.
However, does not leave a "warm fuzzy".

Has anybody experienced something like this? Known cures?

Hello, there DarthSLR, Thank you for reaching out.
We will confirm these info with engineers and will keep you updated. Thank you.

DJI Natalia Posted at 4-11 04:31
Hello, there DarthSLR, Thank you for reaching out.
We will confirm these info with engineers and will keep you updated. Thank you.

Thank you! Yeah, please hurry. I will be leaving for a photo trip in a few weeks, would be nice to have everything in order.

Main thing the rc calibration worked for you. I have never encountered that message on any of my remotes. Does seem odd that it would be requesting you to calibrate out f the blue.

Visual Air Posted at 4-11 06:51
Main thing the rc calibration worked for you. I have never encountered that message on any of my remotes. Does seem odd that it would be requesting you to calibrate out f the blue.

I have never had that issue before either.
Yet again, I have never had pretty much any issues with  the previous drones/RCs
M3/RC Pro bundle is holding the record here for sure

UPDATE

Today I decided to do RC Calibration again, even though RC did not complain.

The left stick did not reach 100% and was at about 62% when moving right (East, 90).
Each run I had it improve by about 5%.
After a dozen or so runs I finally got it to a solid 100%.
Hopefully, it will stay that way.

I still have no idea what has caused it to malfunction, to begin with.

Hello, there DarthSLR, we have asked ourengineer.
If your drone could not reach 100% in direction，we recommend that you send it back to us, we
will help to take care of it. You can send the drone back via this link: https://www.dji.com/us/service/repair
Thank you.