Did you only burn UHD films on these blanks? Cloning BD to BD 50 behaves differently when burning and never causes problems.
I can confirm my results for at least the last 15 months. Always the same media code and everything burned to Pioneer at 2x speed. Whether the 206 or the 212 does not matter. Films are still running perfectly.
Thanks re. 15 months and same with BDR-206 or BDR-212 (did not know / recall that you had both of these drives).
So far I have only tested burns of video discs, but they were simply burned using 'write files and folders...' mode in Imgburn where I simply manually select the BDMV folder and then the CERITIFCATE folder and burn them at 4x as UDF 2.6 video mode.
Not sure what you mean "cloning BD to BD50 behaves differently when burning". Behaves differently from what? With what types of burns are you having issues? I only use CloneBD to create the folders, then I use ImgBurn to actually burn the data using the mode / settings I mentioned.