I had Selvala, Heart of the Wilds and Jumbo Cactuar in play. I attacked, held priority after the trigger resolved, and activated Selvala with Kinnan on the battlefield. The Selvala Activation did not give me 10,000 mana, and I ran out of mana after a few Kinnan activations. I think the game couldn't handle such a high number. This was on PC. I did not screenshot or recorded it, but if I ran into that board state again I will try to get those for you.