After setting up phasing groups, saving a model, and closing out of Twinmotion, when I reopen the model my phasing groups do not save and I lose all the work to set up my phasing groups. Sometimes it will save the work but then if I continue work and save again, close and re-open Twinmotion, it resets and once again lose all the work - even the work that was saved previously. Sometimes it seems to save one of the groups but loses all the progress on the others and upon saving, closing, and reopening that progress is wiped once again.
concerning. 
what is your TM version?
2023.2.3. (I haven’t updated to the latest since the license structure changed and am waiting for my current one to expire before I can upgrade)
Twinmotion may have issues with saving and loading phasing groups properly. To address this, ensure you are using the latest version of the software, verify the integrity of your project file, save incremental versions frequently, and contact Twinmotion support if the problem persists.
It seems that if I quit media mode before saving, it saves correctly but if I save while still in media mode it loses all the work.