Officially it CAN be a problem. Go to the IO. But be humble, be nice. Complain yourself, be even shocked how you could forget THE TM30.

Depending the officer it can be fine or you have to pay the fine.

Some years ago I tried to do TM30 online, and I thought I managed. But after 3 months visiting IO to make TM47 and extension, the officer said I have not done TM30. Luckily they understood how stupid farang can be. No extra charge and TM30, TM47 and extension was done at the same time.