What is the problem?
EDIT***NOTE: I totally apologize for the following...
After reviewing the info I used to install (what I felt was OctoPrint) I actually installed OctoPi 0151.
which after reading Gina's notes is a total separate situation in regards to the OS loaded.**
Again my apologies.
So should I also post something within a OctoPi forum??
Both of my OctoPrint instances seem to be running fine but when I drag n drop a file sometimes it will not go into the list, other times when it does when I select Load and Print it does nothing, then again when it does load the job will not start.
I have never seen evidence of an error on screen.
This situation seems to be increasing in frequency.
What did you already try to solve it?
It seems to resolve this I have to restart the OctoPrint server.
Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, octoprint.log, serial.log or output on terminal tab, ...)
Running the TH3D firmware on my Ender 3 printers, vU1.R2.7,
Running OctoPrint v1.3.10 on a Raspberry Pi V3.
I have decent SD cards in both printers but would not call them "Top of the Line"
Both have 8 gig cards in them and I have well over 7 gigs free space in each.
Both are running Pi v2 cams
My typical printing routine is as follows:
The Pi and OctoPrint is always running.
Due to the fact I do not like the Ender 3's screen lit up while printer is turned off (Pi powers LCD) I typically unplug the USB from the Pi. Prior to this I always Disconnect OctoPrint from the printer.
So I come down, turn on Printer, plug in USB. Go to laptop, crank up a session to either printer, Connect, then drop a file in, Load and Print. When I am done. I disconnect, unplug USB, Turn off printer. Wish there was a way not to power LCD from Pi therefore never having to unplug USB... 
Curious are there any plugins or other ways to not send power from USB to printer when turned off?
Figured I would ask
Sorry I do not have any files (logs) I can try to supply some later.