For the people who are having problems reverting to previous patches, this might help:
In the first picture I have made a screenshot of the ParadoxPlaza Games (you own) sections, as can be seen it says I only own EU3 HttT and EU4 Evangelical Unit Pack
However, underneath that is a button to access earlier versions, click on this and it should give you a list of games you currently own that have previous patches you can return to. It shows the full game name, no expansions or patches, simply copy paste the code to steam, as shown in pictures 2 and 3, Then hit check code, this will allow you to open all previously available patches for that specific game, and you only have to do it once
I hope this helps some of the people having problems with this
In the first picture I have made a screenshot of the ParadoxPlaza Games (you own) sections, as can be seen it says I only own EU3 HttT and EU4 Evangelical Unit Pack
However, underneath that is a button to access earlier versions, click on this and it should give you a list of games you currently own that have previous patches you can return to. It shows the full game name, no expansions or patches, simply copy paste the code to steam, as shown in pictures 2 and 3, Then hit check code, this will allow you to open all previously available patches for that specific game, and you only have to do it once
I hope this helps some of the people having problems with this