This patch was bug fixes and one tweak in the UI, and nothing more.
There was a game capture bug fix was because Oculus Rift games couldn't be captured. That's all that it fixed. That fix does not break other games (because we tested). That fix does not affect other games.
So, why might some people have some problems? It's not because of the change, but because I had to update the game capture hook DLLs for 19.0.3, I also have to digitally sign those new DLL files -- however, because code signing certificates expire after one year, I had to use my renewal for this year instead of the old one, which expired. So naturally, anti-cheats and possibly even anti-viruses may have to whitelist the renewal certificate. (Note however that beforehand I contacted most of them and have already white-listed with most, such as Easy Anti-Cheat used with games like Rust/Squad/Paladins, Battleye used with games like ARMA/PUBG/H1Z1, etc. Most anti-virus software has already whitelisted the new certificate as far as I'm aware because I already started using it with 19.0). However, I can't always catch everything. There's always going to be some game that might have some anti-cheat code that may not have whitelisted the DLL yet, or some anti-virus that may not have either. Especially with a hook DLL.
So, if you just have some particular game that's not being captured, please state the game specifically -- yes, it is important. It's always important. If it's all games, please state if you use anti-virus software or not, and if so, which software you use.
In addition, always please include a log file link generated from the help menu from a session where you had this issue happen just in case there was something noteworthy about the case mentioned in there, or maybe something specific to your system that might be as well.
(Edit: Sorry Robinson -- edited my original post because I didn't mean to seem like I was blaming you there, I was mostly talking about the followup posters who were unfortunately fear mongering saying things like "every patch is getting worse!" and things like that when all I did was release a bug fix patch)