It does not seem plausible that you were issued a Non Immigrant Multi-Entry O Visa inside Thailand period. You must have a Non Immgrant O Visa with a Multiple Reentry Permit.. not the same as you describe.
The new somewhat relaxed Work Permit actually mean very little in the overall.. You still must have an authorized employer, or you 'own' your own company as a shareholder Director. Then obtain a B Visa.. People who are married to a Thai National and have an O Visa for marriage may also apply for a,WorkPermit.
Same as anyone on a Tourist Visa who is applying for a WP with fully knowledge that they are next applying for a B Visa and will get that B Visa before the WP is awarded... A person on a 'retirement' visa/extension cannot even apply for the WP without proving that he/she has exited Thailand. Two different standards and processes for exactly the same process.. where the applicant ends up with a B Visa BEFORE being awarded the WP.... This is one of Thai Immigration's many outdated - archaic and senseless rules