Having the same issue with my even Paladin; even tried a config specifically for turn 1, but had no luck.

Use this :

{
"GameCardId":"CS2_101",
"ConfigComment":"Hero Power settings.",

"BeforeUseHeroPowerBonus":
{
"values":
[
{
"comment":"Set heropower cost to 1",
"condition":"my_heropower(max(cost), cost = 1)",
},
{
"comment":"Hero power only cost 1. Natural boost to hero power.",
"condition": "*",
"value":"20",
},
{
"comment":"Play hero power on turn 1 if we have max 1 mana",
"condition":"my_hero(count(), max_mana = 1) > 0",
"value":"50",
},
],
}
}