I have had several issues with 2 or more Rasp Pi3+ booting from USb.Most of the time it boots fine but on occasion it wont boot, The flash drive blinks a couple of times then there is no activity. Sometimes removing/re-applying the power solves the problem. Other times I can repeat this sequence over and over and it will not boot. I try another Raspberry and it may boot right away. Eventally this same PI will boot without me doing anything (other than passing time). This can happen with any of my Rasp Pi3+ and with any flash drive.
UPDATE: I can make this problem show up anytime by removing the keyboard before rebooting. Without the USB kbrd it (sometimesd) will not boot. Soon as I plug in the board it boots fine. For now, I found an old Logitecg fob that I plugged in and that seemed to work. There must be a better way
Anyone have any ideas/suggestions for this problem??