I have a theory about why this happens. In the past i've seen a similar issue with images and video from mobile devices (iPads mainly) when uploaded to web based systems including, but not limited to Canvas.
My theory is that mobile devices have a prescribed up and down position. When you take picture in any other orientation than the correct one, meta data is written to the file saying to rotate is 90, 180, or 270 degrees for playback. The mobile devices and most computers even understand this meta data and rotate it correctly for playback as expected. But when you upload to some web based systems (possibly Canvas), the meta data is either stripped out or just not able to be read correctly by the system.
Again - that is just a guess about what is happening base on my own observations. A fix????? I don't have a great one. For video on iPad in a previous group i worked with we would be very clear on which orientation to have iPads when recording video. I think if you open the images on a computer and then did a Save As, it would save in the corrector orientation without meta data telling it to rotate. So I think that might fix it but can't say for sure.
Sorry, I wish I had a better fix.
Rick