kdevelop lock icon

I am user of Kdevelop on fedora 34 and a longtime user of Kdevelop. With the most recent update 
using dnf, Kdevelop does not open .html files so that they can be edited. Other files tried, (.e.g. 
.js, .txt, sh) are editable
There is a lock icon at the bottom left which only appears on .html files. I have checked file 
permissions and they are all highly permissive.
And I have googled extensive kdevelop html lock, kdevelop lock icon, etc all without any meaningful 
hits.

PLEASE, provide some guidance on how to make the file editable.

and some documentation references on how KDevelop works, what editor it is based on. Thanks in advance
Lou