VBox 6.1.16 automatic resize of desktop not working

[rjrapier]

I updated from 6.1.14 to 6.1.16, changed no settings, and suddenly automatic resizing of the desktop no longer works. I checked the preferences for display, it is set to automatic. It was working just fine up until I upgraded. I have installed both host and guest additions for 6.1.16. Any hints on what I can do to fix this? On the plus side, I no longer get warnings I used to get when I log into the client.

[rjrapier]

Host: Windows 10 64 bit build 1709
Guest: Ubuntu 10.10 (yes, extremely out of date)
VirtualBox 6.1.16 with 6.1.16 guest additions in guest.

[rjrapier]

The auto resize option in the view menu is now greyed out, so I can no longer select it.

[rjrapier]

It appears to be something with the guest additions. It works with 6.1.14 guest additions in VBox 6.1.16, but I do get some warnings at startup. The warnings go away with guest additions 6.1.16, but so does the ability to resize automatically.