The consensus among community members indicates that the first 90-day report must be completed in person at the immigration office, especially after reentering Thailand. While some suggest attempting to file online for convenience, it is generally recommended to go to the local immigration office for the initial report. Subsequent reports may allow for online processing.
Good to know. I've been unsuccessful online unfortunately. (Even the second time). (A hotel filed a TM30 in my name so the one on file did not match) But going there in person was very, very quick.