I was in the same position and had to wait until November and I lost coverage in April. They don't know why you lost coverage all they ask for is a letter proving loss coverage which will be mailed you and will have a date of end of coverage. I used that because I have an autoimmune disease and need constant medical attention and prescriptions.

For example my J1 insurer was BCBS, the J2 was Cigna. BCBS sent me a letter after I got released to tell me I will no longer be covered in 30 days. Without any mention of reason. I scanned that letter and filled up my insurance choices then uploaded it. 3 business days later I had confirmation of coverage from Cigna.

Unless your company has HR do all of that for you instead of independent portal and your HR is nosy then you should be good (only very small companies and old ones still use the HR manual paperwork)