Custom Menu Problem

Hi

Since doing the up to WP4.5 and other plugin updates something very strange has occurred on our website, to the custom menu, instead of having the official titles (in this case artists names) it has gone to a different number for each example of the first one ‘#71 (no title)’.
This has got me stumped, I look in the menu section, all the titles are there as before.
Though these numbers aren’t new to me as a I remember them in the titles of url heading when originally creating the site.
Can anyone help solve this problem, here is the address to give you an idea of what I am talking about

https://powerintheland.co.uk/artists/

I’m using the Tesseract theme.