I have two apps, for my fenix 6, that remain outstanding to be installed regardless of what I do.
ErgIQ and the Battery Widget. They are actually installed on the watch but they persist on Garmin Express and the sync ends with an error each time unless I do the sync twice though the apps stay.
I also do not have the option to delete the update from GE like it shows on the initial screenshot.
I have the latest Garmin Express installed and the latest beta firmware on my fenix though this happened on the latest official release.
This also tends to happen on my edge 1030 though not always so am having a hard time nailing down a specific reason as to why this is happening.