Using Dynamic Child using Groovy and populate

EPM Cloud, OCI Gen 2

I'm creating Dynamic Child using Groovy script, next step to to assign some values to the new created member for some accounts. When I try to use this newly created member in FIX statement I get "Error parsing formula for [<member name> at of after line: .... : Invalid Object Type.

If I use this member on formula side I get an error - Invalid Member name

I can use this member if DB is refreshed, however, my understanding is that Dynamic Child member doesn't require to refresh outline and it's not feasible as refresh takes few minutes.