While i play on xbox, i suspect this is valid for all platforms.
When selecting troops for a delve team, the mana colors are locked in for that Delve. Using all seeing eye as an illustration of the issues…
-blue and green are locked. This means that i cannot filter blue and red and select “all colors” without green also being selected. Merlion is a valid selection for the delve, but i have to scroll halfway through the troops to get to it.
-the color filter can be cleared. However, once cleared, they cannot be reselected, as the lock prevents them from being turned back on. This can be corrected by exiting the troop menu and risking the game locking up trying to load the troop menu again.