Actually everything will be smooth if you will just submit the right document properly. I’ve done KYC on BC before and manage to get my account verified without any issue since I provide valid(drivers license) to KYC my account.
Probably the passport you are using is not the standard passport which they are as reference with their KYC that’s why you encounter this problem. Drivers license is always very easy to approve even on other services so maybe try to get that ID next time.
It also depends on the country, because I know quite well that during documentation or verification of accounts, if you don't snap the edges of the passport or drivers licence we'll it will not be processed properly, theirs one certain time I had issues with exchange and after I have uploaded my document the site will declined my document whereas all the informations in my document are all correct and intact, and I was thinking that my drivers licence or my international passport has expired, until I set my camera well and place my documents on a tiles and snap the document with the four edges, when I uploaded it, it became successful, so you're right for thinking if the document has expired, if the document is up to date, let @yumeyume check if the photographs of documents the edges is been captured properly.
Yeah right, the proper picture of the document is important too since some use an automated KYC services like Binance that approved KYC through the use of bot which is why you can experience automatic declined if you didn’t capture the image properly.
I usually cam scanner for my ID to make a clean image that easily approved by KYC verification since it removes glare and highlights important details on the ID.
Too bad we can’t check the OP ID due to his privacy.