Understanding 74LVC245 datasheet and current source/sink
"Output current" should be read as "current into the output pin". As such, negative values indicate that the pin is sourcing current, and positive values mean that it is sinking current.
The floating issue can be remedied by using a device with bus hold such as the SN74LVCH245A. The bus hold feature holds the input pin at the previous detected logic level, and since the inputs and outputs are connected internally in the '245(A), this will hold the output as well regardless of the state of nOE and DIR.