P+ seems to do that with a number of their shows. You can't find complete runs of some of them. No idea why, but that's their choice at the moment. I'll always go for owning the physical disc for just this reason.
I have yet to see Gunsmoke available in full series on Paramount +. They have the series but they have season 5 or something listed as the first season for whatever reason. The Odd Couple is also incomplete.
Physical media for the win...
It may take up too much shelf space, but anyone who bought it helped make more home video releases possible. At some point, I'd love to pick this up just for the sheer importance of it
I Dream of Jeannie was the biggest disappointment and missed opportunity in years. Slapdash and just an overall botch.
For shows still MIA in HD or even DVD:
DVD
The Green Hornet
12 O'clock High
HD
Voyage to the Bottom of the Sea
V: The Series (1984-85)
Have Gun, Will Travel