cannot generate recurring invoices after upgrade to 2.4.12

Good morning!

I have just upgraded from 2.4.11 to 2.4.12 in an attempt to fix another problem, which succeeded.  Unfortunately, after the upgrade I am no longer able to generate recurring invoices.

When I go to the "Create and Print Recurring Invoices" page, I am presented with some invoices that are due to be generated and sent.  When I click the icon in the far right column, I am taken to the page that has the create and cancel buttons, and clicking the create button takes me to a page that has nothing on it except the main tabs and a "back" link.

The problem seems to occur under all the themes.

I see the following entry in the apache error logs, but I see this for every page and since it is only a php Notice, I am not certain it has any relevance:

[Fri Jul 22 08:56:58.372406 2022] [php:notice] [pid 2432294] [client 192.168.25.212:46648] 0:bob:sysprefs.inc:36: Undefined property: sys_prefs::$time_zone, referer: https://fa.computerisms.ca/sales/create_recurrent_invoices.php?

fwiw; I did not have a default timezone set in my php.ini, but setting it did not fix the error in the logs, or the invoice creation issue.  I think there is a timezone setting in FA some where, too, but so far I haven't found it.

I set $debug and $go_debug to 1 in the config.php file, but I got no additional text on the page and no additional entries in the apache log.

Any other suggestions on diagnosing and fixing this?