I have been having a problem recently (could it be 2.83?) whereby the animations are not showing the selected armature.
Initially they do show but as I work more and more, the editor will only show the selected bones, until finally none of them will show. Also if the NLA is used at all, it's very difficult to get the dope sheet and the graph editor to show again. Usually by switching to and from various bone groups after selecting the animation icon in the Scene Collection.
How do you get the graph editor back after using the NLA? I have attached the Blend file and a screen shot showing the selected elements resolutely refusing to show in the dope sheet. My work around atm is to export an FBX and reimport it into a fresh Blend file.