Yes, I've had this issue since late July (filled out a support ticket back then) and it is slowly becoming more and more frustrating. Being able to turn emails into tasks is a critical part of my GTD flow and without this feature, RTM is losing a lot of its appeal to me. I know I am not a "Pro" user yet but I've been planning on getting a paid subscription (for Blackberry support). Now I am thinking about looking for other options.
There are a lot of things I love about RTM and I appreciate the team working on it but IMHO gmail extension support is definitely the Achilles' heel of the service. I understand that they cannot control what Google does but surely there has to be some way to address this issue quicker.

This has been my only issue with RTM. For me it's also the most used and needed work feature.

"Create task" disappears all of a sudden and then again appears. Have no idea how to solve it. I tried disable and restart of FF3 but that didn't work today.

+1 having the issue...

My box:
- Win XP Pro, SP3
- FF3.0.1
- FF Addons: Better GMail 2, Evernote Clipper, Foxmarks, Gmail S/MIME, Google Gears, PDF Dld, RTM4Gmail, Twitterfox

Cheers

One of either: Better GMail 2 or Gmail S/MIME may be conflicting with RTM4GMail..

I disabled them both, restarted FF. Adding task functionality via starring item worked again.
Re-enabled Better GMail, restarted. Adding task still worked.
Re-enabled Gmail S/MIME, restarted. Adding task still worked! Odd...
I'll try one more reboot.

I would also like to add that RTM4GMail occasionally fails to load on launch/restart. Reloading GMail via F5 usually remedies the situation.

Upon restart of FF, RTM4GMail still fully functional.

I don't know what to say, really. I'm happy enough. :)

Cheers

I hope I have got the solution for this...

The only thing that I find different from the day I install it was the log-in sequence.

Open the browser, login to RTM, then login to Gmail and IT STARTED WORKING FINE FOR ME !!!

Still not fixed yet. I am trying to get away from Outlook task and am a pro user. Trying desperately to not use MS. RTM, we need to find a solution to this problem. RTM is too good a tool.

I followed mediaarts path and disabled two extensions: better gmail 2 and stylish. I was skeptical about the results b/c I had done that already back in July when the problem first appeared and had no success. Lo and behold, after restarting FF, the "create task" functionality came back. I enabled better gmail 2 again and create task is still working. I don't really use stylish that much so I decided not to enable it for now -- hate to lose the feature again!
In any case, something strange is going on.

We're regularly updating to handle new versions of Gmail's code (as their changes can affect parts of RTM for Gmail's functionality), but if you continue to experience problems, we'd much appreciate it if you can submit a Gmail issue report via our support system.

Please select the issue that you're experiencing from the list on the left, try the troubleshooting steps (if any are shown), and then submit your report -- this will help us greatly in resolving Gmail issues, as your report will provide all the information that we need to investigate further.

Thanks!