As may have been surmised, the two apps that gave me grief, were originally stand-alone installs. Only later were they offered & updatable (solely) via the App Store.

Perhaps the issue indeed relates to how the app was initially installed.

Curious and curiouser... shocked

Harv
27" i7 iMac (10.13.6), iPhone Xs Max (12.1)

Those who can make you believe absurdities can make you commit atrocities. ~Voltaire