Suggested fix (unconfirmed): Farm foil points to hit shop jackpots for a 25% chance to get a relic booster, and check the relics page for remaining question marks.
Suggested fix (unconfirmed): Unlock the upgrade that grants a 25% chance for a relic pack on a jackpot, then grind jackpots while speeding through levels between visits to the skill tree.
Suggested fix (unconfirmed): Update the game and open another relic pack. If still stuck at 38/39, roll the shop to hit jackpots for a 25% chance of getting a relic pack.