Hi Eeugene,
That is very odd.
Try disabling the ‘selected only’ icon in the top bar (it’s the thing that looks like the cursor arrow).
See if that makes a difference.
To me it looks like the bone is active but not selected (or vice versa).
Disabling the filter should ignore that and show you all the drivers.
Let me know if you still have any issues. There’s a chance it’s a Mac bug.