Universal subtraction-free Laurent expansion conjecture for TP-bases

Let a cell in the nonnegative Grassmannian be given, and choose any TP-basis, meaning a minimal set of nonzero Plücker variables from which the other nonzero Plücker variables can be expressed as subtraction-free rational functions.

Universal TP-basis conjecture. For any cell and any TP-basis, every other Plücker variable in the cell can be expressed as a subtraction-free Laurent polynomial in the variables of that TP-basis.

The source says this conjecture may follow from the conjecture that all TP-bases are mutation equivalent. It is therefore presented as conditional and remains open in the source.