There was a mistake on my part and I forgot to uncomment some parts of the TestStruct.h so that would explain why I wasn’t reproducing the issue. Going back knowing that, I tried building the plugin with RunUAT (step 2) but ended up failing due to the exact same reason it fails in step 4 with your plugin. From what I understand if it’s failing here, then this isn’t a bug as the Category should technically be required for something using BlueprintReadWrite.
Here’s the log file: UnrealBuildTool.txt