After running one of our in house functions CADWorx no longer applies grouping to the pipe objects.
I have checked system variable setting, ambiguous function and variable names but can find nothing obvious.
Can any one offer advice?

can you explain what the function does?

It is an xreference management tool. We define a query for part of the plant and the function determines what xreferences need to be attached.
Not the sort of functionality that you would expect to clash with grouping.
My thoughts were along the lines of function names or global variables.
I have checked the system variables but I cannot think of one that would stop grouping.

What is your pickstyle set at?

I have found the problem to be a global symbol 'info' needs to be set to 1.
Our function used the same symbol name and had not declared it so the CADWorx symbol was overwritten.
Thanks for all suggestions.