Can't create folder inside assets

[ChanceD11]

hi there i'm trying to add a folder "videos" under assets.  It creates the folder.. i upload the video.. but it doesn't stay!  Everything disappears.  Tried Chrome.. Tried Safari.. Tried updating both and then updating my Mac OS.  I keep creating a videos folder and the I'll even click "save" and then "publish" website.. but then when I go back to edit my theme.. the folder and its content have all gone.  Any ideas?  Very frustrating.

[ChanceD11]

video had to be re-encoded.. no warning from website but it prevented folder from being saved.. gave the illusion of the file disappearing.. a warning that the file format is the issue would be appreciated