I hope you got the visa sorted out and are already retire in Thailand 😊 If so, can you pls share how you did it? We are in the same situation - my partner has been in SG for 14 years on EP and he couldn’t apply non-O visa via Thai embassy in SG 😔
The Thai embassy in Singapore only accept a retirement visa application from Singaporean or PR. They won’t accept an application from other nationalities even you have the EP.