After turning on add a signature to the end of sent emails all my groups disappeared in Outlook
Hi Bobby,
This seems unusual as the option you have enabled will not conflict with your groups created in Outlook.
I suggest you to check with Outlook settings to add/remove groups.
Also, I request you to disable AVG and check if there is any changes in Outlook.
Refer the article for https://support.avg.com/SupportArticleView?urlname=Disable-AVG-Antivirus