The regional_channels supplement does not include ZE2 postcode. ZE1,ZE2 and ZE3 are all valid postcodes for Shetland.
ZE2 added to the deprecated regional_channels_by_postcode supplemental file.
I'll carry out an updated postcode check against the current lineup files to see if any other postcodes are missing. The postcode lists were made available by a third party and may therefore contain errors and omissions.