Communication between IC and microcontroller (Teensy 3.2)
You seem to be overlooking (or at least mishandling) the fact that these parts are built with a bus interface where the /OE and SEL signals as well as the internal position data latch are sampled synchronously with a clock input which you do not seem to be driving.


You need to generate a low-to-high transition of the CLK signal to latch the count into the readout
You need to generate a high-to-low transition of the CLK signal to latch in chosen values of the /OE and SEL signals.


On second examination of your code, perhaps you are trying to use a free-running clock asynchronous to your reading.  That, however, is extremely unwise.  First, you don't know that a suitable clock edge will happen between when you set the /OE or SEL and when you try to read the data.  Next, you do not know that an undesired clock edge will not happen in the midst of reading data, causing you to end up with a corrupted value that contains some "old" bits from before the clock edge and some "new" bits from after.  This would be particularly bad if it happened across a transition such as 0b01111111 to 0b10000000 or similar...

You may have other problems as well - your question is not complete without a schematic diagram of how you have wired up this chip.