A visa does not guarantee entry. This is a universal rule eventhough the chances of refusal are minimal. It was like this for Canada and it is like that for Thailand.
This is a normal process. When I immigrated to Canada, I faced similar situations. Obtaining a Visa does not guarantee entry in the country. It is always at the discretion of the officer. They are just doing their job and cooperating like you do is the way to go.
Anonymous participant I am sorry, I am confused. It almost seems like a mistake on their end. I have seen cases where they ask for proof of income(s) when applying through soft power. But I have never heard of a case where they mention workaction. I would advise 2 courses of action:
1-Send them proof of income for the last 6 months.
2-Email to confirm that they understand that you applied through soft power and not workaction.
I would favor option 1 as I usually do not like to argue with government employees.