WAVE upgrading is broken or bugged?

How is anyone supposed to upgrade WAVE cards to +10?
I have one card +2. I try to upgrade it with Jokers. It fails even with stabilizers.
I upgrade Jokers to +1 so I upgrade my +2 with +1. And the game doesn't let me do it. I remember back in the day I used to upgrade with same +X. Now it doesn't work???
Why is the game forcing me to upgrade +X cards with +0?

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