@theruttmeister
Answered my own question:

https://www.youtube.com/watch?v=FFCo5P0iQAI

I'd check your drive lever. Looks like a fundamentally flawed design. No wonder there are lots of upgrades on the market.
If they had just made that hole 4mm and used a shoulder bolt...
Guess that's how you get to a $300 printer.

@dc42 thanks for your answer.
Are layer comments the same for every slicer?
Could you answer two more questions, please:

How DWC determines layer change? If I'll place any G-command (one or block of commands) with summary Z, DWC will take it, divide per layer height, then show me correct info? You wrote, that it looks for Z moves , so, it looks like "last Z" minus "pre-last Z" = "layer height" for DWC, then "last Z" / "layer height" = "layer quantity"?