This has been my deep suspicion all through your experiments. I don’t think your lean mass measurements necessarily track with actual muscle tissue in any way. There are just too many variables changing too often and I fear that you body is perpetually in an adaptation phase of the latest experiment. Also, there is always going to be some lean mass that goes as long as you are losing fat mass.
Here is why I’m so suspicious. I have an impedance scale myself. I bought it shortly after I began keto and right when I began CrossFit, which was the most intense exercise I’d ever done in my life. The numbers it generated were completely mad seeming for over six weeks before fat and lean both started going in the right direction. I think when we make radical changes to diet or exercise our body has hormonal and inflammatory responses that can last weeks and throw the results of these tests into complete uselessness since any small change in muscle tissue can be completely swamped by the weight changes from other lean sources and fat loss can be hindered by the stresses of the changes.
I really think you should be judging your muscle changes by strength. Lean mass is so noisy that it’s very possibly useless for your purposes and yet actual strength changes are easy to track.