Own a lot of AMGN a month prior to ex-div and it's now the 10th and have not received the div paid on the 6th. Clearly IBKR is earning the float and waiting for the client to complain.
I believe that IB sends you a message in the online message center about upcoming dividend payments. The amount, ex-div date and the payment date is usually listed in those messages. Unless you have opted out of receiving those messages.
If you like div's you might want to take a look at CION. Pays over 15% and trading near recent lows. It's a BDC.
I'm have no info on this specifically... for IBKR and DIVs and AMGN... But !! I am increasingly impressed by the number of customers and clients (the public) of different HUGE companies who finally understand how they are getting screwed over from the way so many HUGE companies take a little $$ from millions and millions of customers each month/week/day and they invest YOUR money into the overnight or longer commercial paper market... and reaps millions for free every year. Outright theft. Also known as playing/earning float. Total Rip Off. Like... Comcast... Bank of America... IBKR... Other Brokerages and 1000s more... etc., etc. For example is Ionos a HUGE web hosting company. They will, many times falsely (sloppily) over charge you... When you call and complain they say it will take 5 to 7 business days to return your money. All the while they reap the float. PayPal too. Others...
Why I own Charles Schwab...They are killing it on the float!! Compared to Fidelity (which timely throws my money into a money market fund...Above 4%), Schwab "slowly" throws my money into their bank. It earns about .5%...They say "well it's safe there". No other choices... I enjoy the stock price...But grumble under my breath every time I wait for the posting.
Fidelity and E*Trade are the best in biz for sure. IBKR's good where it matters as I filled at mid all day in SPX. The problem is that 35% of me thinks it would never have hit the account if no message.
I recently had a surprisingly helpful conversation with the support team about something else. Like something has changed in the way they reply to customers, I want to think. Maybe you can try your luck and drop them a message. Usually speaking to the support team is even worse, but who knows, maybe they are doing better now.