Randomly receive 'Whoops, looks like we couldn't publish your post' emails

I post three times a day to four networks (Twitter, LinkedIn, Facebook and Instagram) via Adobe Express scheduler - moved across from ContentCal.

My connections are set up fine but randomly several times a week I get an email saying 'Whoops, looks like we couldn't publish your post' and a button to take me to the post 'to fix it in a few clicks'. Usually it's for LinkedIn. On the post there's a message saying 'As this technical issue is less common, our team will need to look into this to identify what went wrong.' But there's no indication that this happens, or to get it to happen.

It's an intermittent issue and there's no indication what the problem is. Sometimes I can 'retry now' by refreshing the feed connection. Sometimes it will work if I delete the image and upload it again (exact same image ...) And sometimes even trying everything, it simply won't publish again. But then often the next one that's been scheduled will.

This happens too many times per week for it to be something I can ignore. It's super frustrating as it feels like the software/platform just isn't stable enough for me to rely on it (and I like many others was dumped from ContentCal with the promise that it would work practically the same - but I never had this problem on ContentCal).

Please help!