[BUG] "Print Completed" not poping up after print has finished

[phenolplus]

Bug Description

When a print is complete, a popup showing "Print Completed [time] ... [OK]" would come up.
Some times it doesn't.
The printer will be stuck in printing mode, showing progress 100%.
Because of this, you cannot move axes, filament, or start another print.
If you click [Pause], the printer errors out. (failed to get response from pause command)
If you click [stop], the pop up appears and the print is completed.

Note: The g-code file is indeed complete because the last line was executed (M104 S0).
I notice this only happens on consecutive prints. It never happens on a first print after power on.

Steps to Reproduce

0. Print from SD card from root folder.
1. Start a print.
2. Wait till it completes. Then start another print
3. Wait till it finishes at 100% and stop.

Expected behavior: [What you expect to happen]
The print finishes and a popup occurs in the screen.

Actual behavior: [What actually happens]
The print stays at 100% progress.
The printer does not respond to [pause] button.

Additional Information

This can be tested with single line g-code file.
It never happens on first print after power up. However, sometimes it doesn't happen on a second print either.

Machine: stock i3 mega-s
Firmware: MEGA_S_v1.5.2.hex (prebuilt release)

[potatobarry]

Could reproduce, same Firmware, same Printer.

[knutwurst]

That's indeed a bug. I'll take a look. Thanks for reporting!

[phenolplus]

Following up with what I think may be the same issue/cause. When filament runs out at 99% progress it will hang. The printer has responded to the no-filament error (by pulling back filament, homing print head, and turning off heater) but there's no pop up "Lack of filament [OK]" warning. The printer instead becomes unresponsive (pause fails). The print is not recoverable.