Likely in September (2019), through looking at my profile using moderator tools (which I no longer have access to since I resigned as a moderator in early October, and I tried very hard to avoid using any moderator functionality while I was waiting for my resignation to be processed), I noticed that SE has an e-mail address on my account which should not be associated with my account, and which I could not change. I contacted SE using the contact form and asked for this to be changed. In later e-mail communication, I specifically requested on October 8 that someone at SE look at it, and was quite specifically told literally within minutes that it was in the queue for someone to look at.
On October 25 (2019), as the e-mail address had not been changed (I verified this through a data portability request less than half an hour earlier), I submitted a GDPR data rectification request through the web interface.
On December 4, I submitted another data portability request wherein I noticed (once it finished, which for some reason took a few days) that the change still had not been made. Also on December 4, I sent a follow-up e-mail to firstname.lastname@example.org, as the web interface says to do in case of additional questions, referencing the Oct 25 data rectification request by ID and asking when I could expect it to be honored. I never received a reply to that e-mail.
On December 22, I submitted another data rectification request through the web interface.
As of January 10 (2020), both data rectification requests show as "Company Approval Requested". Both are properly confirmed by me (I even have a screenshot of the second data rectification request clearly showing the green "your request is being reviewed" popup). I have received no feedback on either.
All that as a preamble to my question: How long should I expect a GDPR data rectification request to take to process? Particularly when that rectification request concerns only a single piece of account information?
This is not a duplicate of Can a GDPR request take up to a month to process? because this question is about data rectification requests, not data portability requests.