I recently used UA miles for a one way award from DPS-BKK-USM. It required an overnight stay in BKK.
I tried to connect via KUL. I was able to find an award easily from DPS-KUL, but there were no MH metal flights on. Paid rates between KUL and USM were considerably higher than Bangkok Air between BKK and USM.
On my return, I bought a one way ticket from USM-BKK on Bangkok Air, stayed in Bangkok, then had an award ticket on.