Yeah, your situation needs a 4K compatible receiver with two hdmi outputs, or a splitter after the receiver. In the case of the OP, a UHD player with dual outputs would work by sending the audio to the receiver and video directly to the TV. The downside is you lose OSD from the receiver for...
There’s always the option of a UHD player with dual hdmi outputs. I haven’t researched the cost to get players with that, but it seems like the best solution in a lot of cases.