I used R19 today and made some changes to my preset folder which contains several objects which builds a whole character in a DIY manner, meaning it contains parts of character.
For some odd reason, R19 randomly deletes the objects from it when I perform a certain process on the said preset which gets its data deleted. The deletion percentage is random as I have inspected during different istances of it happening. It does not happen everytime, more like 50/50 of it to happen.
Process of Reproducing the bug:
Unlock the preset that has Read Only via C4D
Take out an object
Modify the object
Delete the original object from Preset and replace it with modified one
Make the same preset as Read Only
Before I exit Cinema4D, I check if all objects I need to be on the preset was on there, so I don't know what is happening on my rig. There was no crash on Cinema4D so crashing is will not be a reason on why it doesn't have half of the contents.
This is the forum for people using the Maxon classic API or Maxon API with c++ or Python.
Your issue seem to be more a use case.
The other problem is that we don't support R19 anymore.
My suggestion is to try to reproduce the issue with our last version of cinema4D (using a trial version) and open a ticket to our support.
(by the way i was able to reproduce it with R23)
without further feedback, we will consider this thread as solved by tomorrow and flag it accordingly.