As Bigstock hardly sells anything for me, it took a few months before I noticed my portfolio at BS was not increasing anymore (while I was still uploading to SS).
A short e-mail to Bigstock and I got a (surprisingly fast) reply :


"Thanks for reaching out to Bigstock Contributor Care. We truly appreciate your contributions to our collections during all these years! Unfortunately, they have reported that the Bridge Program between Shutterstock and Bigstock is closed; it will remain that way until further notice. If you like to submit the same content you have approved from one platform to the other, it will not be marked as a duplicate, however, you will have to do it manually. "

Must say I cannot feel happy or sad about this, but just in case you wondered, it's not a bug, the "bridge" is closed.
And no, I have no plans to start uploading manually.  Not for 9 dollars per month.

Maybe people will see your post and notice. Yes it's closed after about ten years.

Update:
 Got this from BS today:

Thank you for your patience while we reviewed your case. We have received news from our Higher Office, and according to them, the Bridge Program for existing contributors was discontinued in April 2022. In this case, if you wish to have your content on Bigstock, we suggest you upload the content manually.

To me, Bigstock is just useless. A waste of time.

Easy to agree.