First of all, I studied in Japan. After I complete all graduate courses. There will be 3 years to submit my thesis. During this time, I drop school and work in a company. So my professor removed all my information from the lab (%100) like I was not there, even Alumni name list. I would like to ask is it common for other schools.
Consider your relationship with the professor at the time that you left. There are at least two cases I can think of where a professor may remove your information from the lab page.
- You didn't finish, and you are no longer part of the lab (not quite alumni). It's not clear if you will finish. A lot of unfinished students can make a bad reputation for the prof.
- The professor does not want you to represent the lab.
As you probably know, Asian culture is a lot about 'saving face'. The professor may feel disrespected by you taking a job before finishing the thesis. Or possibly even taking the 'wrong' job.
One place that the professor is very, very unlikely to remove your name is the lab publications list. Work on publication, and use that as your work reference rather than the lab webpage.
If possible, try to discuss your research with the professor.
It's normal to remove old student content from the group page. Get your own page if you want.
I'm not as used to seeing ABD or "got masters and quit" students removed from alumni list. Most professors want to emphasize how many students they have helped and take credit even for those who did not finish. However, it's still a very minor thing, and "his dojo" and not your concern.
Really, I think worrying about stuff like group inclusion when you are gone is a little "off". I mean you left the nest...you shouldn't even be snooping that page...or at least act like you are above it. ;-) Keep your eye on the current job who is paying you. And just submit the thesis and fight to get your union card...don't let it get away. Priorities...