I missed it then, but your comments during the posts I was replying to did seem a bit like you were complaining which was why I mentioned it.
I've had other games I've modded were Ren'Py went super finicky with some minor changes that had to be sorted out. Also I always due a code diff between versions to patch the changes into my mods and minus the new content the only changes made code wise between the 0.045v3 and 0.048v4 releases were some dialogue clean up which wouldn't have affected saves and the changing of the labels tab positioning possibly needed due to Vinyard changing from Ren'Py 7.4.11 in all releases up to 0.45v3 to 8.0.3 for the 0.48v4 release. Now I was able to load all my previous saves with no issue with the 0.48v4 release but as I've already mentioned, Ren'Py can be more finicky than a pussy (cat or female human) for some and easier than a prostitute for others.
Hopefully with the move to the 8.0.3 SDK, we will see less issues related to Ren'Py. Though I do know those on older hardware may not be able to play the game anymore.