USPS tracking NOT uploaded, failed marketplace notification

[arcoiris7979]

Since July 27th, some of our order's USPS tracking numbers can not be uploaded. After we process the order batch from ShipStation, some orders show "Failed marketplace notification" alert. These orders are marked shipped but without tracking. Then I tried to upload tracking manually but it won't let save it.
Last several days I have 8-15 per day out of about 50 orders without tracking.
ShipStation told me that eBay recently does not accept USPS recycled tracking numbers. But I believe that USPS has been doing the same practice (recycled numbers over 120 day old) for years maybe. Not sure why this issue (not able to update tracking on eBay) happened since last week.
I also talked to eBay, they said they were aware of this problem, and they acknowledge that it's a eBay site issue and it's affecting some other sellers (don't know to what extend).
It's kind of frustrating since these orders show "tracking not uploaded" even though they were shipped on time with USPS tracking. And we don't know if and how long will it take for eBay to fix this problem.
If it's only affecting a few sellers, it could take a while for eBay to identify this issue, or they might not even find the issue and fix for us.

[inceptions]

Have you considered printing your labels through eBay? Or another service?

[arcoiris7979]

I did. But we have been using ShipStation (postage from Stamp.com) for many years, I really hope this is a temporary problem. If printing labels from eBay, it's not convenient at all to print 50-80 orders once. Especially the packing slip does not have the SKU numbers that we need to pack the orders. Can't customize the packing slip with the info we need. Even we can, don't think we can save the customize version for future use. Can't we?

What other services do you recommend?