This is the second instance where I've encountered and reported this problem.
(First report here: https://feedback.wizards.com/forums/918667-mtg-arena-bugs-product-suggestions/suggestions/50032566-wizard-s-lightning-does-not-see-that-slickshot-sho)

While I still can't rule out an interaction between Wizard's Lightning and Slickshot Show-Off being the cause, this time was slightly different and feels like something else is happening here.

This time, after casting Reckless Charge, Wizard's Lightning again showed its cost as 1 Red.
This should have left me with 1 Blue to cast Consider, but instead that land was tapped to pay for Wizard's Lightning as well.
Instead of winning the game by swinging with an unblocked 10/2 flyer, I could only swing for 8 damage and was forced to concede
(Logs and screenshot attached.)