InApp Emulation window not appearing in BTD Battles

I have an Yuntab K107 (Android 5.1, rooted, Busybox installed, Xposed not installed, CPU locked to 1300Mhz), that I have Lucky Patcher installed on. I have the modded Google Play Store installed (latest version) and the target application (BTD Battles) is patched for InApp emulation as well. When I try to make a purchase, nothing happens. I don't even get a popup asking if I want the item for free.

InApp emulation has worked in other apps I have tried so far, isolating it to only this app.

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