Characters blinking/disappearing issue

Does this occur after loading a save file? Does it happen while you play a new game?

In the majority of cases after loading a save file

VS is not very friendly when it comes to updates & using save files that were created before the most recent update because the save data contains a lot of data, but it's possible that it contains data that is no longer relevant or lacks data such as new conditions, values & various other things that have been added, removed since the previous version.

Ideally you shouldn't allow people to use the save system until the game is ready for release & you should try to get the game as bug free & finished as possible before officially releasing it otherwise it's highly likely you will come across random issues created by loading old save files at some point or another.

VS is not very friendly when it comes to updates & using save files that were created before the most recent update because the save data contains a lot of data, but it's possible that it contains data that is no longer relevant or lacks data such as new conditions, values & various other things that have been added, removed since the previous version.

Ideally you shouldn't allow people to use the save system until the game is ready for release & you should try to get the game as bug free & finished as possible before officially releasing it otherwise it's highly likely you will come across random issues created by loading old save files at some point or another.

This is true and I already knew it

Strange. I've played various Daedalic games in the past that were developed with 3.7.1 & below & don't remember coming across that issue. Maybe Alex could provide some insight as he was the lead dev on 3.x & below. He's not so active these days, but you could try & grab his attention with a private message.