Apologies for the succinct
nature of my original post , as I thought it was actually quite clear.
I have found the answer to my original question.
Before local io could stamp passport with visa ,
local immigration office was waiting on an update from changmai Immigration office and inturn changmai Immigration office was waiting on permissions/update from Bangkok immigration.
Delays apparently caused by staff shortages at Bangkok IO due to COVID
Thanks for all your replies most appreciated ????