Hello, I'm an itch.io admin. There are no known issues with our submission system, and we had no downtime during the submission period. The submission time is very strict, if you miss it by 1 second then your submission will not be allowed.
I checked the upload dates & times for your project, and I see that the files you have uploaded were uploaded after the submission deadline for the jam, so my guess is that you missed the deadline. This jam is configured to block new files from being uploaded after the submission deadline, so even if you had a submission page up, your files would not have been able to be added.
Thanks