Accessing c++ variable in Animation Blueprint with strange behaviours


UPROPERTY(BlueprintReadWrite, EditAnywhere, Replicated)
bool bIsRunning;

I set this variable in my Character.cpp from a Binded function.

When I open Editor and run game it will always give me this error (after i close the PIE window):

Blueprint Runtime Error: "Attempted to access missing property 'bIsRunning'. If this is a packaged/cooked build, are you attempting to use an editor-only property?". Blueprint: WP_CharaBP Function: Execute Ubergraph WP Chara BP Graph: EventGraph Node: Set Running

Which is my AnimationBlueprint, where I Cast PawnOwner to my CustomCharacter and then access bIsRunning and use it to trigger an animation.
When I get the error above, this variable in the animBP says “variable out of scope”. If I delete it, then drag out from the cast>CustomCharacter I can get “bIsRunning”, hook it up, hit Compile, no errors.
Run the game, and it’s fine. No errors or anything.

I can close the editor, reopen, and it is still fine - no errors.

This happens random but often. Any idea what could be causing this?