Activity Monitor displaying only processes, no other info
This afternoon I opened Activity Monitor (in the course of answering another user's question), and found that the window is devoid of information other than the Process Names. Normally, columns are shown that indicate CPU utilization, process uptime, number of spawned threads, etc., such as in this image borrowed from Apple's Activity Monitor User Guide:
In my case, there is nothing displayed other than the Process IDs. The header bar with the column labels is likewise blank. Secondary-clicking in the header bar shows the column selection dropdown, and the appropriate items are checked, but not showing. This is the case for all tabs, showing just the CPU tab below:
Selecting and/or deselecting columns to show has no effect. I have tried force-quitting Activity Monitor and rebooting the Mac, also with no effect.
I have iStat Menus installed, and that appropriately displays the processes and their CPU utilization, RAM allocations, etc.
2019 16" MacBook Pro, macOS 10.15.6 with SU applied.
Suggestions on next steps?