GH6 focus peaking bug?

Good luck finding anyone who might help you solve this problem.

Unfortunately, if one searches mentions of "GH6" in this little sub-forum, any references are largely tangential or hypothetical. Various independent GH6 user forums exist, but often don't have much traffic, or people pose questions and no one answers. None of the "how to" sources I see, whether related to the GH6 or GH5, delve into your particular scenario and bug.

Steven Litton shoots video with a GH6 and he posted a video about manual focus controls. It does not address your particular issue. However, perhaps he can help, whether by replicating or diagnosing the problem, or by referral to other GH6 users who might know.

There is a 2019 discussion of Panasonic focus peaking problems at the EOSD forum , which may be of help, even if it is not particularly conclusive.

Contact with members of the Vimeo GH5-GH6 User Group is another potential path.

My dumb guess is that any use of a flat profile or DR boost will conflict with the focus peaking function. In low light, FP may not work at all. My dumb assumption is that focus peaking works well only in high contrast or sharp standard profile modes. If compelled to shoot in reduced contrast or DR boost modes, both AF and MF become a challenge. MF will depend on your own visual reconning. If the aperture is wide, there might be lots of trouble.

In other words, what you call a "bug" might instead be a "known issue," a fundamental constraint, that cannot be undone by a firmware fixed, but only avoided by work-around measures: either use settings where focus peaking works, or else find substitute means of achieving narrow DOF focus or deepening your focus.

Are sure that your Sony a6500 does not present a similar problem? Were you using identical settings under identical conditions? Were you using a low contrast LUT or a DR boost? The a6500 uses PDAF, but that would presumably not matter if you were using manual focus.