I'm also encountering this issue. It specifically occurs when Unity tries to serialize a NetworkVariable<FixedString32Bytes>. I am able to set the value of the network variable and read it again ...

[Message: NullReferenceException: Object reference not set to an instance of an object. #541 Closed astef89 opened on May 31, 2024 ...

We show you how to fix Object reference not set to an instance of an object error prompt which you may see in Microsoft Visual Studio.