Some spots have more than one correct answer, worth the same expected value. In GTO these are called splits, and the app handles them differently depending on your level.
Before level 7
Any one of the correct actions counts. The app explains it during your first split: “Some hands have multiple correct answers with the same EV. In GTO this is known as a ‘split’. For now, just try to choose any one of the correct answers, they are both equally correct. Later at a more advanced difficulty, we will focus on memorizing splits.”
From level 7
Splits start being checked in full. You get a level-up message when it happens:
You’ve leveled up and unlocked splits! Now you will need to identify when a hand is a split by tapping the “Split” toggle and select all the correct answers!
From then on a split spot needs all of its correct actions selected. Turn on the Split toggle, then pick each action that belongs. Selecting only one of two correct actions returns “Sorry, the correct answer is a split”, which is the partial-credit message: you were on the right track but the spot wanted both.
The level that matters here is your overall level, not the level of the individual category.
Seeing the split itself
When a hand is a split, the feedback panel says “The best answer is a split” and lists the actions involved. View Ranges shows the same thing on the grid: a cell divided in proportion to how often each action is taken with that hand.