This is caused when the security profile that the Capture Broker service is using to connect the Dimensions Dataset does not have adequate permissions to post the Transactions type. Note: this does not mean the profile for the human user logged in to the system who is processing the invoices, but the profile set for the user ID used by Capture itself, this is usually SA or CAP.
To resolve, from within Dimensions:
Click System, then click Security.
Click Profiles.
Scroll through to the profile that the Broker service is running under
Click Edit, then make sure that Invoice register, Transactions is ticked.
Click Save.
If you then try and push through the Transactions from Access Capture, they should now come through.