Sourcerer Free version no field to enter /...

Hi I'm, using j4.4.3 and sourcerer 10.1.1
The Tag Syntax tab has no field to enter or change the Tag Characters type to << >> for example.
See screen shot

I have tried clearing caches and uninstalling and reinstalling sourcerer.
Any ideas how to fix this?
I'm happy to delete plugin directories /db tables and reinstall if i know which ones i should delete.
Thanks

I have turned on Joomla Debug and Set Errors to maximum
In the console > Issues tab (Chrome) i can see:

Incorrect use of <label for=FORM_ELEMENT>
The label's for attribute doesn't match any element id. This might prevent the browser from correctly autofilling the form and accessibility tools from working correctly.
To fix this issue, make sure the label's for attribute references the correct id of a form field.
24 resources
Violating node

I tried using Firefox but same issue here

I loaded the FPA Script

Hi Peter, I can try.
I have other identical joomla sites all working fine.
With the custom stuff on the admin side do you mean the coloured btn links i have added to the top position of the atum template?
I havent done any other custom stuff as far as im aware.

Thanks Peter,
I have unpublished those modules that had the custom stuff in admin area, but its the same issue.
I noticed some of my fields in Global Config are also missing so i think you are correct that its not to do with sourcerer

Hi Peter,
I ended up rebuilding the entire site from scratch.
Even replacing all the core files didnt fix it!
Thanks for your help.