I have been unable to use the online system or the app since I got a new passport 2½ years ago. First I was told I had to make one report in person and then it would work - it didn't. Then I was told I had to leave the country and make one report in person and then it would work - it didn't. I have tried the app and four different browsers without success, so I have been making in-person reports right through the Covid pandemic (I didn't fancy risking the snail mail option).
I registered for the new system when it was announced on Thai Visa the other day, the process was clear, simple and quick. Yesterday I successfully submitted my report in the morning (using Chrome), also very straightforward, and received my confirmation in the late afternoon.
The most amazing thing is that after 20 years of constantly having to provide more documents and information than in the previous year for the same process at Immigration, the new system REDUCES the requirements! The form no longer requires your TM6 number, the mode of transportation by which you entered Thailand, your flight number or equivalent, your type of visa, and the date to which you are permitted to stay. I can only hope that if this crazed reduction in bureaucracy doesn't cause the collapse of Thai civilisation in, say, the next six months, they might consider extending the approach to other processes. Imagine no longer having to provide 20 pages of photocopies of documents that they already have from every previous year's application to extend your permission to stay...