Do you get the Pizza Wheel or just Wheel of death? I have this problem too and regularly ask for help but @Toufiq has looked and "no problem found"
@see https://www.joomshaper.com/forum/question/13864#qa-answer-67507
This is definitely one of the symptoms...
https://archive.joomshaper.com/forums/update-latest-sp-page-builder-pro-3-4-9-gone-templates-layout-and-add-section-library
I was using Opera, but this happens in Chrome too.
I think it is a problem of sequence - the joomshaper licence is (somehow) reset to my admin account details and then when you attempt to access the page this causes a cyclic login failure which renders the page "locked" but you can't re-edit (but if you just click on it - not preview or live edit - it is returned back to "not locked").
BUt after this, you cannot ever see the page again. It is perfectly fine to "view" but no more editing :(
I really would like an answer here as my confidence in using Joomshaper is shot :(