Why doesn't cross-posting from Instagram to Facebook work?

Question

iPhone

Given: Instagram business profile and Facebook business page, they are linked to each other (including in the app). There are also "personal" profiles in both social networks.
When trying to "send" a post from Instagram to Facebook (checkbox "share") on the Iphone, the message "sent" appears, but nothing appears on the Facebook page.
I tried to restart the phone, delete applications, re-login and so on (as described here , for example) - it did not help.
Suddenly someone came across and knows what is the reason? Apparently some simple thing, but he could not find it. Thank you!