It appears as if there are once again issues between Rusev and WWE. The Blugarian Brute has not been seen on RAW since before the Royal Rumble PPV and it now looks like a contractual dispute between the two parties is to blame.
According to the Wrestling Observer Newsletter, a contract dispute - presumably relating to him signing a new deal with WWE - is the issue here but there are no specifics on what's happening at the moment or when it's likely to be resolved. This would also explain why WWE appears to have dropped the storyline involving Rusev, Lana, Bobby Lashley, and Liv Morgan.
There have been hints that Rusev is unhappy for a while now and it seems like there is indeed a chance he's going to end up leaving WWE if something can't be done to resolve the situation. With any luck, though, he's just playing hard ball and this will all be resolved soon.
Stay tuned for updates!