Ok, weird situation. So setup is a Tiagra 10spd, 10-34T cassette both on my Zwift Hub and regular wheel and 36/48 Chainring. It’s been shifting fine on the Zwift Hub. I recently needed to change my large chainring so I went with a larger 50T while keeping the 36T small ring as I like it for climbing. Also got a new chain so I adjusted the length accordingly using the big to big technique. Also adjusted the height of the front derailleur to account for the larger diameter 50T. Adjusted with my normal rear wheel and took it for a spin and everything shifts fine. However when I put it on the Zwift Hub, it no longer shifts up to the large chain ring no matter where I’m at on the cassette. What’s weird when I disconnect the power, it shifts normally across all gears.
That is strange that turning the power on and off should make a difference.
-First thing–that 10t cog is technically smaller than Tiagra specs specify. They say min top sprocket size of 11t. I don’t see that this would make a difference in front der shifting though. Just noticing.
-Assuming you’re working with a medium cage, and we’re talking 4700 Tiagra and not an older version, you haven’t exceeded the max capacity of the drivetrain. (50-36) + (34-10) = 38, and 4700 medium cage has a max cap of 41. So that shouldn’t be an issue. (If you’re on a short cage version, I don’t see how it was shifting well at all previously 
)
-when you set the chain length using big-big, you made sure to not run it through the rear cage, right? And then used that distance plus two rivets (not two whole links) for the size?
-Did you adjust the angle of the front der too, as well as check the limits?
What happens when you try to shift when it’s on the trainer? The front der moves outboard–does it not push the chain out far enough? Is it scraping/rubbing against the inside of the big ring?
What happens when you have it in the big ring, put it on the trainer and power the trainer up, and shift off the big ring? Big clunky sounds, or normal shift?