Menu Settings Keep Reverting to Default. Version 2.6

Please help! Version 2.6. My client’s site menu keeps losing its settings, the settings keep going to default. We really need your help.

What would cause this? Have you ever seen that?

So far, it has happened twice, but it has never happened before. My dev guy fixed it after it was noticed, and it happened again, I don’t think anyone

We did do a recent update and added WP Importer, and WP Exporter to push some pages from a dev environment. Those are the only changes we have made recently. Do you know if you have any conflicts with these plugins.

I can only share the URL in a PM, it is an important client of mine, and I am feeding other people by having the client, so I could really use your help.