Did they test with the PIS fully working (even if they put stickers over it) and with the doors being released and a member of staff tapping the dispatch card, though? It seems to me they didn't?
It is notable that the testing of the C2C 720s I've observed on the WCML does seem to be being done with the full works, i.e. doors releasing at each stop and the PIS set up correctly, even naming WCML stations it calls at on test. This does confuse people a bit but you could always put stickers over it, and there are canvas banners blocking boarding at each door in case a passenger does open them either through confusion or an enthusiast mucking about.