Just to say that we passed a similar phase with DS, from 10-11 months old lasting few months, in which when we went out he would have stood up and called for us. I did a modified version of WI/WO: after saying goodnight I waited in the room for few mins giving my back to the crib (so no interaction), and when he was calm (but before he was asleep) I went out. If he stood up and cried, I waited for few mins outside to understand if it was a "I need you cry", then when it escalated I went in and did PD, calmed him and stayed with him a little more in the chair and with my back to the crib and then repeated it. There were nights when it took also 1.5 h, but the majority of times it needed less than 30 mins. This phase passed one night (he was 14-15 months), when he decided he didn't want me there and he fell asleep alone. From that moment, he always fell asleep without us in the room.
It could be also UT: with a single nap of 2.5 h I would aim 12h night, 13h night seems a little too much for me, but it depends from LO's sleep needing.