How to reproduce:
1. Open the attached project
2. Build and run on Android device
3. In menu click first or second button
4. In the main scene click on bottom button (left or right) and scroll the shop down to it's end
5. Click the same button again to hide the shop
Result: You will see that it's not closed. And somewhere will be glitches

Reproducible: 5.5.0b1, 5.5.0p3, 5.6.0b3
Couldn't check for a regression because Unity is not forward compatible. Tried to recreate simpler project in 5.4, but mine didn't cause this issue neither in 5.4 nor in 5.5.

DUT(repro):
Sony Xperia Z [L36i C6603], Qualcomm Snapdragon S4 Pro, Adreno 320, OS 5.1.1
One Plus X [ONE E1003], Qualcomm Snapdragon 801, Adreno 330, OS 6.0.1
DUT(no repro):
LG G5 [LG-H850], Qualcomm Snapdragon 820, Adreno 530, OS 6.0.1
Samsung Galaxy S 5 Neo [SM-G903F], Samsung Exynos 7 Octa, ARM Mali-T720, OS 5.1.1

By Design: one should use camera clear flags to clear different collections of the buffer information (for example Solid Color)