I am running into the same issue. Just finished two seasons and attempting to start the third season and it goes to the AMC subscription. 5 to 7 pair of but trying to look online. It says all seasons are free with commercials.
I tried continuing- and also starting from home screen picking He— on Wheels. All require subscription when attempting to start 3rd season. 🤷♀️
I was able to select all episodes of this show from Season 1-5.
I performed a Search for it, then selected the Roku Channel. Was not asked for the AMC Subscription (though I see it as an option.)
Does the same thing happen if you try to watch it on the online Roku Channel?
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A little weird that what you described is what occured to me online. On the online Roku Channel, Season 3-5 gave me the AMC message (subscription). On my devices, I can watch it just fine.
It does show as Free on Roku Channel. Normally, if limited to a certain number of episodes, it will say "Free episodes available" in the results. This is not the case here.
Paging @RokuDanny-R , @RokuMary-F , and @RokuKariza-D who can perhaps provide more info and look into it.