wasn't there a different sort order of menu items in the burger menu a few days ago?
By coincidence, we have a similar issue on our stage as well. Does anyone else have the problem as well? Could be a problem with Khoros Communities Release 19.7.
I have heard from our TAM that this is a known issue with 19.7 (but it's better than the completely blank menu some communities saw w/ 19.6!)
I suggest open support ticket on this, or email to email@example.com.
They can rectify this issue and will let you know the cause on there side on community.
TBH... Ive had an issue with my site for ages.. where the popout menus are painfully slow to update and reflect changes made to the site nav.. I often have to wait a day for it to update. No real time thats for sure, Ive raised tickets in the past and had some luck with quick fixes when updates appear to have been "stuck" but the issue persists.
Just a quirk of the platform, just my opinion anyway...