Gonna need more details here. 

I click on the tab where I collect the rewards and it's just a dark screen. But I can push the back button to go back and play the game.

i

i

TThat's 

moved to Loading Issues

what device/platform are you on? if mobile, are you using a motorola?

Yes to both questions 

Bit of a good news/bad news situation since we know the reason behind that:

i

Ok thank you.

So one last question. 

Am I going to be compensated for what I can't get now later on?

I am having this same issue, yes I have a Motorola

Would have to talk to support on that one, couldn't hurt to open a ticket.

I have the same issue, but I'm on an iPhone.

 same issue but on pc on one account and same issue on other account which is on samsung phone

For those still facing problems, if on iOS: 

"Ask them to clear cache. On iOS they will have to Offload the Raid app, unfortunately

iOS: settings, general, iPhone Storage, pick an app and click Offload app (this will uninstall the app, but will keep the documents and settings will remain. Then install an app back"

If on desktop, please clear cache then try the usual uninstall/install.