Outdoor runs keep getting corrupted

My outdoor runs keep getting corrupted. It was fine for about 2 months. I use courses to create my route and set up PacePro. All of a sudden, every outdoor run can't be synced. I've tried uploading the file to garmin connect and I get the message "One of your files was not accepted by the system. Please contact Support for assistance." The files are also VERY small compared to previous runs. The one today is 9KB and the last run that got synced correctly was 334KB. What's causing this issue? How can I prevent it from happening again?