I’m on Android and experienced this bug for the first time during the Tuesday delve event.
I selected King Blood wood’s spell but it wouldn’t let me target and enemy. It greyed out the board and my allies like it would normally, but when I clicked any enemies, it’d only show their details. It wouldn’t cast the spell nor do anything else.
I was stuck and had to retreat, losing that sigil…
To clarify the screen shots, after you cast a spell, when you click an enemy, it selects them as the target. It shouldn’t bring up their details, which makes it impossible to target a troop.