In April I bought a Logitech MX Keys for Mac wireless keyboard and in June a
Logitech MX Anywhere 3 Wireless Mouse for Mac.

I use them with a 2019 MacBook Pro running the latest Catalina OS and a Dell 24 in., 4K monitor.

They keyboard has run fine but the mouse is occasionally jumpy, something that appears common according to comments on the Internet.

No problem when I use an Apple keyboard and mouse.

I tried running the unifying software, but it failed.

Hope you can fix this problem which spoils the pleasure of an otherwise great mouse.