i keep getting an error message " the value specified is invalid " when trying to list products BUT it does not tell me what value is invalid - support are not help

I'm trying to add my offer of a product sold on Amazon by several other sellers. However I only get error message 5885. I have contacted seller "support", but as per normal the support element seems missing. They have told me to update the details of the product, but I'm obviously not able to do that because I get the error message. I hope they would try these things themselves and not just send generic messages without any understanding of the problem.

@Seller_mIRnuhdx7l5sN @Julia_Amazon @Sakura_Amazon_ @Sarah_Amzn @Simon_Amazon @Spencer_Amazon @Winston_Amazon

Please can you assist with this?

Case: 10012615922

Hi,

I am listing a gaming PC which I branded and made, so i bought a UPC code on barcode mania as explained on youtube but I keep getting this error message when I try to submit the product.

If i tick it does not have a brand it automatically chooses "generic" and i still get the error message.

Or if i write my brand name into it it says its not a brand that exists on the system.