Storyline 360 - audio disappears in lane, then reappears!

I had an interesting thing happen in a course this week. 

I have a course with several slides having standard mp3 audio. Nothing fancy, just straight reads. I moved this course file up to the network for archival reasons, and another person on the team published it for review in Articulate 360.

Some of the slides came up without the audio upon review.

When I downloaded the .story file from the network - the same file I had uploaded, and the team member had published - in about 6 slides (out of a couple of dozen), there was no audio. The audio lane was in the slide, but the audio itself was missing!

So I opened up an older copy of the course, and proceeded to copy & paste the audio from the old version to the newest version. When I did that, *magically* the original audio lane suddenly reappeared! I then deleted the copied lane, immediately saved the new course, closed out & came back in, and the audio (in the old lane) was still there. I then proceeded to fix the rest of the slides with missing audio in the same way & resaved the course again. It was published and reposted, and now the errant slides are playing back fine in review.

There was no difference in the audio files I edited & imported to the Storyline file. There were all saved the same way, imported in the same way, and none of them had any strange characters in the name. Only a handful of the slides with audio came up this way, as if they had lost an external link.

I'm wondering if there is an underlying database within Storyline that might get befuddled when a .story file gets loaded to a server, or if another person on the team publishes it. Still it's odd that once I pasted the file back in, the old lane re-appeared. It's like the lane was turned off, but it wasn't.

I've had other issues with audio in Storyline - audio drops in video files come to mind - but this one was a bit of a stumper.

Anyone else experience this?