Hi there!
Sorry for your issue.
I have just tried the quickstart at my end and all looks good. Here is a screenshot below:
https://prnt.sc/Ptyhi4GFvOs4
And I have logged in to your admin area also, and tried to create test menu items and test property in soliders component. Only the single property menu item has this issue as I can see now.
However, I have also noticed you are using PHP version 7.4.23 https://prnt.sc/CSYeYCuBU2Bi
Would you please lower your PHP version and then clear your Joomla and browser cache to check if this helps?
If it doesn't help, is it possible for you to let me know what you have done recently when all was working? That would be helpful for me to find out the issue.
As a final step, you may try to remove this installation totally and reinstall the quickstart of the template if there is not so many changes done by you already.
Best Regards