I downloaded the IFC app and I've used it previously, but now if I click on it the IFC logo displays briefly and it returns to the Roku homescreen. I tried deleting it and downloading it again but no dice.
Please make sure when removing the channel, that you restart the device before adding the channel back again.
If the issue remains unresolved, I'd recommend reaching out to IFC directly to report the issue and request additional support. Many channels on the Roku platform are developed and maintained by the channel provider directly, and they'll be able to best assist. If other channels are working correctly, and you only experience this issue on the IFC channel (app), that is likely an indication that the issue lies within that particular channel. In these cases, the channel provider will need to investigate the issue in order to help resolve it.