Kayes refused to convoy

[TeaLeaf]

Kayes resource (Senegal) is traded to the CW and there is an unused convoy line from it all the way to an idle factory in the UK (Newcastle).

The program however refuses to use it.
I can make it accept transportation of the resource to Newcastle by defaulting or overriding, but as soon as I close the production planning screen, the Kayes resource is again idle (you can check by reopening production planning).

This started happening after I patched from 7 to 8 (latest hotpatch).