Can't find address lists under Personal Address Book on one of two systems
Using TBird 15.10.1 64-bit on my Windows 10 desktop system, I find under Tools | Address Book a down arrow to the left of Personal Address Book; clicking on it displays all my created address lists, which are available when I compose a message to send.
Using 15.10.1 64-bit on my Windows 11 laptop, the down arrow does not appear and I have no access to those lists.
Am using IMAP on both systems. Tried importing lists as a CSV file; no effect. How can I get access to my address lists on both PCs?