Client inputs not working after build on networked project...Sometimes.

I’ve been trying to fix an input issue on a project I’m working on. It’s a cooperative shooter project that has been worked on by other people before, and was working correctly before.

All the inputs from the client players, be them mapped inputs or keyboard inputs, stop working sometimes after a build.

Not even on the local side I’m able to get any input to register with a printString, at all.

The server (which is not a dedicated server, but also not a client) can register inputs normally. Always.

Sometimes player input works in-editor, then I package the project and it works normally. Sometimes, after packaging, all input from the player completely stops working. If that happens, usually restarting the engine works to temporarily fix it. Cleaning the project also tends to work, but I’m not fully convinced there’s even a relation between the facts.

I can’t possibly think of a reason why this is so inconsistent.

I’m using UE 4.18.3

Thanks in advance for any help!