Hello Piotr,
Sorry, this is Benroy Fernandes... I checked that we have customers on that version that have not reported a similar issue. I also checked our internal bug reporting, and no bug has been reported. As you mentioned, it could be that it is dependent on a specific form type, or a field, or perhaps an image used.
You mentioned that some customers are facing it, so it's not just one then. Yes, if it is possible, can it be tested on 8.5 210213/85360166
with one of the customer's data, to start with. If it still occurs, then we will need to try and identify what is different between the Sales Invoice and the Sales Order form.
I also meant to ask if there was any HAL code related to the delivery or invoice function. And also... when did the issue first start occurring? Was it soon after they did an update of SERP? or after the updated to Big Sur
/Benroy Fernandes