Cintiq 21UX - No longer accepts display from all inputs. Any ideas?

I have a Wacom Cintiq 21UX (dtz-2100d/g).

The display has a built-in DVI-I cable.

The following inputs will display a picture on the device

• DVI-I direct input
• DVI-I to VGA (using the supplied VGA to DVI-I adapter [88741-9100, Molex])

The following will no longer display a picture on the device. But they were working until recently:

• DVI-I to HDMI (using a 3rd party adapter)
• DV-I to Thunderbolt (using Apple thunderbolt adapter).

Does anyone know why these adapters would suddenly stop working? I have tried them on other displays, and they work perfectly, so I know the adapter is not a problem.

The unit comes with DVI-D to DVI-I adapter (88741-9400, Molex) but it makes no difference if this is used or not with the adapters that no longer work.

Here is a picture of what the pins look like on the built-in DVI-I cable:

It doesn't look like any of the pins are bent.