I’ve come across this, and this might be something related to that specific server and maybe timeouts. It only happens to me occasionally but it’s always either he same server. Either Jerboa isn’t able to handle the more poplar servers/the settings for the account, or the server is having the issue. I’m not an expert, I’m just trying to voice what I’ve seen in my end.

It’s probably not the best option, but I’ve found it easier to subscribe on a main browser with the account. It still will keep your subs in Jerboa, but people also get funky about not having the app be a full all around experience.