Also from my side, thank you for the quick response.
(a) We did see "ERROR:firmware.runtime.rtio_mgt:RTIO sequence error involving channel 4" error message in the log
(b) Adding 8 ns delays did fix the issue.
Is there any reason why this is not a fatal error? The fact that the output signal is simply not generated could be very problematic. Unless one notices the log message, it would very difficult to debug (considering that the Gtkwave output reports that the output signal WAS generated)
PS: As far as I can tell, the worst-case number of output events that are scheduled at the same time (with zero delay) happens at the beginning: 3 events in the initialization, 2 events in blink_output, and 1 event in blink_other_led. That is a total of 6 events, which should not exhaust the 8 available lanes.