Why does the top menu keep shredding to bits?

Hello.
Are you getting any reports of top-menu problems, or even footer menu problems?
I’m using your free theme, and to date, the top menu has been shredded twice by surprise, at two different hosts, with no apparent cause, or certainly none the host is able or willing to identify. I love this theme, it’s very upsetting that the menu keeps falling apart. I just put up the main tabs again, but the subtabs are still missing, lots of work to do on that. About 30 menu items were shredded off the site suddenly a couple of days ago, and I have to reconstruct the bottom two rows, and check the whole menu, which currently has about 80-100 newsletters embedded one per page from 2008-2017. And more.
www.remarpro.com says it could be insufficient PHP memory, but the host says my PHP memory is 256.
Is this then a database problem, a wordpress glitch, vandalism, or a THEME glitch?
Because the menu is the most vital part of my website, time-consuming and hard to reconstruct, and I’m facing doing it all again a SECOND TIME now thanks to its being shredded again by surprise.
Below is a link to a pdf of the red errors in my menu dashboard seconds after the current shredding happened. Can you please tell me if this is your theme that’s doing this? Or if not, then guess at what the cause could be? Because I can’t live with the prospect of constantly reconstructing the menu when it shreds by surprise.
https://u.pcloud.link/publink/show?code=XZ2FWNVZDSE0G7JeCuBwLpS5LAisxu7UbYUX
Thank you.