My Elements not being saved

Design elements are not being saved.
The 'Save' function works but when the element is inserted it inserts the default format. 
For example, I saved a checklist (with green checkmarks), but when I insert it on another page, I get the default checklist with blue checkmarks.
 

Hi
thank you for your feedback
I will check that
CEd

I forgot to include that, to isolate the source, I did the following:
Installed PageBuilder CK on clean, latest versions of Joomla 4.x and Joomla 5.x, without any other extension, but the problem remained.

I have tested but I'm not able to reproduce the issue
What I have done :
- inserted a new list item
- edited and update the arrows color to pink
- saved it as "My elements"
- inserted the new element in the page

and I got a pink list as excepted. Can you please give me the steps to reproduce the issue

Given that various installations of Joomla (same hosting provider) were giving same problem, and the common thread being PHP, I upgraded PHP to latest version - which turned out to be the issue.

The problem is now resolved.
Thanks for your help.