Across a dozen-plus playthroughs, the ONLY time I was able to become a Thane in Riften was when I belonged to the Thieves Guild. When dealing with the pro-Stromcloak jarl, it doesn't matter that I've "helped her people" far in access of the number of times required, and that I own Honeyside. She NEVER offers... unless I belong to Thieves Guild. If she gets replaced by Maven Blackbriar, Maven won't even open a dialogue menu.

Really makes me want to assassinate Maven Blackbriar. (She's the real power in Riften, and the Thieves Guild is her primary tool.) Too bad that's not an option.

It's actually a known and extremely annoying bug.

I've had it happen to me once or twice, but yeah, you're supposed to be able to become thane once you do the skooma quest. Maven's supposed to offer it immediately after capturing Riften for the Empire.

Odd thing about this particular hold is that you're supposed to help people before you're even offered the title. Given the number of bugs associated with this particular quest I'd say someone screwed up bad.

Maven becomes the jarl after the empire take over? oh god that sounds like hell for riften.

It doesn't really make a difference. Laila pretty much let's her do whatever she wants because she's a gullible [censored] and her steward also works for Maven. As Maven says when she takes the throne, her title of Jarl is just a formality--she's always controlled Riften.

not really, she is still in charge either way

Laila's rule is just a puppet regime, with Maven pulling the strings

Its certainly possible to become a Thane of the Rift without belonging to the TG, I've done it several times without any problems.

No TG quests count towards helping the people of the Rift so whatever is causing your problem I don't think its anything to do with membership of the TG.

My character became thane of the Rift with no TG and no problems in our last playthrough. Only done that one time and had no problems. Reviewing UESP wiki, I do see that some bugs sometimes occur during the thane quest however.