Budget : error when hidding field

Hello,

i'm using customised screen for budget (hidding all values HT to keep only TTC value because we paid VAT).
When i set a "transfered value TTC" on a budget, i get this error, exactly like if hidden field is no longer present : 
Investiging further it seems that, if "availableTransferedAmount" is hidden, calculation fail.
Restoring visible state for "availableTransferedAmount" restore the right calculation.

So, field seems to be unreachable and not only hidden.

Regards,

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