I've been having the same issues since the last update. Every now and then the game will just spin with a loading icon when buying something, finishing a run, using the tavern, etc. This occurs on my android mobile, iOS Apple iPad and windows computer, so it is definately not device dependent. It also occurs even if I am using 4G cellular or home WiFi.
The issue is 100% Raid's servers, which currently seem to be struggling. I've only been playing for about 9 months but never had this issue before, as the game has always been responsive. I've even tried to uninstall and re-install the game completely thinking that it was a buildup of cache or something, but no luck.
I'm concerned with the upcoming fusion even that I won't even be able to participate, as the game just simply isn't responsive. Even trying to use my multi battles a day is a gamble, as the game can just spin and time out after any run, which then requires me click either "Re-Login" or "Retry".
Edit: It's probably worth mentioning that I'm in Australia, if that helps identify the server I would be using