Tip for issues syncing between podcast subscriptions on Mac / iOS:
Syncing must be enabled on both devices.
Under Podcasts, go to Preferences –> Advanced –> Sync Subscriptions Across Devices
Under Settings, go to Podcasts –> Podcasts Settings –> Sync Podcasts (switch turns green)
When you next sync your iOS device using Finder, go to [my iOS device] –> Podcasts –> Sync Podcasts onto [my iOS device] –> click off which 'casts / episodes you wish to sync.
Hope this is helpful, I could have used this info 2 weeks ago.