Rob, ran a few build updates after your OE-A fix and noticed that the ET8500 didn't install the HbbTV ipk but did for my ET7x00.
Just checked and there is a typo for the ET8500 in meta-oe/recipes-oe-alliance/enigma2-plugins/enigma2-3rdparty-plugins.bb .... reads enigma2-plugin-extensions-newxtrend-hbbtv_4.0-r0_et8500.ipk.ipk that is double ipk
Not sure why my build didn't flag it but it ran OK to completion