I've been creating buttons on my pages that early readers can use to click right to an assignment or discussion. While they show up on a number of the ipads, some show a box with a "?" inside. In addition, I have made buttons that show up in my course (on an ipad). I shared them to commons. But when used by the next teacher they show up as "?". Is there a way to correct this? Is there a certain file size to stay under for jpegs or buttons? Is there a certain version of the iOS on iPads that this is a problem?
If I remember correctly - this is caused by not having access to the image. Check that the image is actually part of the course by confirming it's in the Files area of the course (or the image is hosted somewhere that anyone would have access to). It could be inconsistent across your users because some users are part of the course where the image was hosted. So Student A took MTH 101 with you, and you hosted the image there, and now you're using the same image in MTH 102. Student A can see it because they were in MTH 101, but student B can't because they are new to your program.
We have not heard from you since you first posted this question on September 8th. Did the reply from @abunag help to answer your question? For now, I am going to mark your question as "Assumed Answered". If his response looks good to you, you can mark it as "Correct". People will still be able to comment on this question if there are questions.