What should I do if my husband's Thai visa was issued with the incorrect reason?

As soon as you get a visa you need to check the details.

a Thai Wife absolutely does not need a Work Permit to work inside Thailand, so both people do not have the Thai Nationality, How could you accept on receiving this Visa the text based on Thai wife?

I understand mistakes are made by an Embassy, but accepting being a Thai and then travel with that visa is taking a risk as denied entry is a big possibility by using this incorrect visa.

@Rene *****

To be completely honest, the two ways to rectify this would be

Method 1 - send your husband to the thai consulate in either Vientiane Lao (which requires a booking to use) OR Savannakhet Lao which is walk up, and have them apply for a 90 day Non-O based on being married to a foreigner who legally works in thailand.

He'd need the original marriage certificate, copies of it, your passport data page, your Non-B visa, your extension of stay, your work permit, possibly your contract with your employer, AND possibly a letter from your employer stating it's okay for him to apply for a 90 day Non-O trailing spouse visa. It'd be 2000baht to do that.

OR

Method 2 - bounce him out and back to get a new a 30 day visa exempt entry. Then you two could go to the immigration office where you got your extension and he could apply for the 90 day Non-O inside the country based on marriage to a foreigner who legally works here for 2000baht

You are gonna be doing a LOT of hoop jumping dealing with the MFA about correcting the visa (especially seeing as you already entered on it 😕 ). I mean it's doable but I don't know if it's doable in the time you have left on the initial 90 day stamp he got when he entered.

Once a visa issued and used, <- seeing as you didn't catch it was issued for the wrong reason and entered on it 😕 the only way anything can be corrected is at the Ministry of Foreign Affairs Office out at the Government Complex on Chaengwattana Road.

They are the ones that control the visa issuing OUTSIDE the country at the thai embassies/consulates. They'd have to contact the issuing consulate, get the documentation submitted, review it and then make any notation or correction to the visa. The type is correct Non-O, just the reason it was issued was wrong.