Epson et-8550 top/rear feeder ignored with some custom big size setting

[soswow]

Hello,
After bunch of research, trial and error I still can't make it work.
I have a piece of paper with 279 x 1388 mm size (width of A3). When I set printer with custom size as well as Epson Print Layout it ignores top feeder (where I've loaded my paper) and tries to get it from casset 2 (with plain A4).
Here is what I know after troubleshooting:

• Back feeder removable thngy installed correctly
• Top feeder works. I've tried with A4 paper and it printed fine.
• After I printed A4 test print, I forgot to change the settings on the printer itself (so it thought it has A4) before trying again with my long paper. It started printing. I was happy until I saw it was printing something cropped and narrow. I cancelled. Sent job had proper (279 x 1388 mm) size.
• I know it can do big prints. Previous panorama print was as wide (A3 width) but shorter (~900mm)
• It doesn't give any error anywhere when I send a job. It just start trying to grab A4 from the casset (I've emptied it so that I don't get A4s wasted)
• Printer's driver is up to date
• I've restarted printer and Print Layout

I feel like it is not happy with the size I've entered into the printer. I thought I could get some logs so I can see what it is not happy about, but I couldn't find it even in it's web interface with admin access.

Any ideas?

[soswow]

I've done some more troubleshooting.
I found a setting in the printer (Settings > Guide Functions > Paper Mismatch) that is off by default. I've set it to ON and now it started complaining.
From the message it shows me (see attachments) it sounds like it thinks the job was to print A4. If I force it to take paper from the rear feeder, it will print it as A4 (I've placed plain A4 paper sideways to simulate A3 width). The other attachment is my config of paper in printer and Epson Print Layout.

[soswow]

I tried printing from Preview (mac) using system print dialog with the custom size specified. Same story.

[soswow]

It seems like the mystery is solved.

Found this on DPReview:

Be aware that the ET-8550 has a bug (or did have a bug) that it will not print longer than 1200mm (47.2"), despite the manual saying it will. If you have difficulties, reduce the custom paper length to less than this. Good luck.

That sucks

[soswow]

I've printed a smaller (1200mm) version of what I wanted to do. (lego block for size reference)