Retrace and evoke on permanents (endurance with six)

If a player controls Six (gives all permanents in GY retrace with additional cost of discarding a land), has Endurance in the graveyard, and wishes to retrace Endurance and also evoke it (assuming multiple green cards to exile from hand), it SHOULD work, according to rules 502.81a and 409.1b, but the interface demands I pay GG1 to play and does not give me the option to cast it with both evoke and retrace.

Start by tracing how the game handles casting a permanent from the graveyard with retrace and how evoke is selected and paid. Reproduce the Six and Endurance scenario described in the issue, then verify that both alternate costs can be chosen together and that the resulting payment matches the rules.

Written by the indexing model from the issue text.