Since I also ran into the issue of a broken SobiPro after upgrading to Joomla! 3.9.3 from 3.9.2 I updated SobiPro to the current version 1.4.10 which fixed the broken SobiPro-issue. All functions appear to work fine except the "Alpha Listing" which can be switched on and off within the template configuration. The Alpha-slection top bar is visible but upon selecting any letter by clicking the link (which leads to https://website.com/index.php/template/list/alpha/a for the letter "a"

[Got error 'repetition-operator operand invalid' from regexp]
To me, this seems like an error message thrown by MySQL - I currently can not figure out what kind of regex the system does not like. The usual search-function is working fine.
Thank you for your assistance!