I'm using Linux, which may be relevant.
I currently have "v1.4.1.0 (ea04)". I'd like to get the open beta. In the Steam properties for the game, I go to the Betas tab and select 1.4.1.1. Steam tells me I've opted in, downloads 3.2MB and patches. But when I start EU4, it now tells me I have "v1.4.1.0 (bae9)", rather than "v1.4.1.1 (1f0b)". I exit the game and ask Steam to verify the cache... and it tells me everything is fine. I can opt out of the beta, get ea04 again, and the whole problem is repeatable.
I currently have "v1.4.1.0 (ea04)". I'd like to get the open beta. In the Steam properties for the game, I go to the Betas tab and select 1.4.1.1. Steam tells me I've opted in, downloads 3.2MB and patches. But when I start EU4, it now tells me I have "v1.4.1.0 (bae9)", rather than "v1.4.1.1 (1f0b)". I exit the game and ask Steam to verify the cache... and it tells me everything is fine. I can opt out of the beta, get ea04 again, and the whole problem is repeatable.