Onboarding new payout rails - unexpected liquidity constraints

We're expanding into a few new payout corridors, primarily LATAM. The due diligence on the local PSPs seemed solid, good reviews, competitive rates. But once we started pushing volume, particularly in $BRL, we hit immediate friction. Their posted liquidity for USD conversion into local currency is significantly lower in practice than advertised. It's causing real delays and affecting our user experience. Anyone else experienced this disconnect between stated capacity and actual operational liquidity from regional PSPs, especially when dealing with higher volume FX conversions? How did you mitigate it beyond simply splitting volume across more providers?