Nothing, in fact, the last tests I opened P3D with no controller and tested standard F3,F2 and F1 to be recorded in the log and waited for one exact hour and voila the increments changed. Tested then the same keys which gave me the same entries that the first ones. Tried the same test with default "standard.xml" and "standard.xmlx", the same files with "read only", my own modified files with "read only", tried the three options INCREASE_THROTTLE, THROTTLE_INCR and THROTTLE_INCR_SMALL and the result is always the same.
Very strange, really, I never had this problem with FSX, P3D V3... and across the internet I found only two posts from years ago. So I believe it's something difficult to be tracked.
2013 https://www.flightsim.com/vbfs/showthread.php?279421-Throttle-unresponsive
2016 https://www.prepar3d.com/forum/viewtopic.php?t=119494
I know, but I hope that instead of sending the THROTTLE INCR directly which even with the keyboard sends different steps, (I guess that smaller or higher depending on the time being pressed), sending an exact number of steps could bypass the culprit. I don't know, I'll try later a flight EBCI-LGAV with the NGXu and see if when on final approach I found the solution and get the throttles working as expected.
Thanks!