I've gotten bitten by this a few times now... usually when I'm trying to rush a change into the sequence and get it out quick to the display.
My setup:
I have my files located on a desktop computer where it is easier to edit with audacity, 'save' a little faster. The directory on \\DESKTOP is C:\xLights.
I have a notebook where I make changes often. I share DESKTOP's directory and mount it as X:\ on \\NOTEBOOK.
Most sequences have no problem, but I have a couple sequences that use the Picture effect, or Glediator effect that save path to the file based on the PC I used at the time. If I used the notebook, then the path has X:\... if I used the desktop the path is C:\xLights\
The problem is when I 'save' the file to generate the xseq file... if I saved on the same machine I authored the sequence, it works. But if I save from the wrong machine, then the effects are lost in the output file.
Unfortunately there is no error to tell me what happened.
Some suggestions:
... alert the user when the files are missing... maybe at load time would be best to avoid lots of repetitive messages
... when importing a sequence, alert the user -- or browse to find the new file
... look in the work directory for missing file
... force the path to be the current directory and remove the path name after browsing for the file
