"When I insert a design outline file (.can) created in a different version of the software, some motif fill areas are blank."
If your design contains motif fill areas using My Motifs created in 5D or 4D Design Creator, the My Motifs will not initially be present, and therefore cannot be used in the mySewnet™ Embroidery Software. Use Backup MySettings in 5D or 4D Configure, then restore MySettings in mySewnet™ Configure. Then, in mySewnet™ Digitizing, re-select the My Motif for the motif fill area in your design.
"I cannot see thumbnails for my design outline files."
Thumbnails can only be seen for .edo design outline files, they cannot be seen for .can design outline files from 5D and 4D Design Creator. Use Insert to view the contents of a .can file.