Login to Account Management and you can submit a trouble ticket there. It's easy enough to find the mechanism once you've logged in.
?
The cost of the US Equity and Options Add-On Streaming Bundle is $4.50 per month and the US Futures Value PLUS Bundle (which you also need) is $5.00 per month.
?
So for a monthly sum of $9.50 you could have saved yourself a lot of hassle, not to mention the amount of time I and others have spent on this topic today. Besides which I would never expect delayed data to give me any realistic indication of how the live feeds perform: they're probably pretty good, but there's no reason to expect them to be – they're free after all!
I'm running the latest TWS API version and the most recent TWS version. As described, this TWS version seems to be flawed since I cannot reliably request delayed (!) market data. I would love to use this version, really, but it drives me crazy.
Later, I discovered the files section of this group and under API old versions, you can find a 972.1x TWS which I've downloaded and installed. It was built on 20th February 2020 (so roundabout two years old) and I can easily log in. There is only the message, that I should update. I then started my client without changing anything (!), I didn't even change to another TWS API version. Now, it runs absolutely fine - no problems anymore, delayed market data runs in very fast and without any issue. I guess, that this should be enough of a proof that newer TWS versions seem to be buggy regarding this type.
@Richard: To be honest, my plan is to subscribe realtime data later. As for now, I want to use the delayed data because I'm still developing my application (thus I don't need realtime data for now) and ironically, I also want to check how stable and realible the TWS API is before I'm going to invest any money on that. ;-)
Do you know a channel or an IB mail address I can report this issue to? I only found the contact form which allows to enter 200 characters or something like that, which is not enough to describe this problem.