This was already discussed in the Tavelo Arow thread, as I originally posted a link to Oak's website.
The story I was told from Tavelo was originally the Arow was supposed to be exclusive to them. Hence why Adapt listed and then removed the frame from their website. However, Tavelo realized they needed to recoup more costs so the frame design was extended to Oak CC for sale.
I wonder if the BB is still undersized...
In a huge shock, Oak says they were the original development partner but needed more funds to own the mold fully.
Oak sells its version with a BBInfinite one-piece included. I don't understand if the issue with these frames is Tavelo and Oak is paying for more QC and going slower (e.g., waiting for the final production processes) so these things are caught, or if there is a design issue with the BB that PT tried to use, and that BB Infinite has a design that works even with the undersized bore. I do know that Shimano, Sram and Wheels Manufacturing account for this in their designs. Some people have also questioned if the Hambini BB is toleranced correctly in reference to the spec. Not being a machinist, familiar with BB86 spec, nor having used a Hambini BB, I don't have an opinion on this other than I would try a two-piece BB first to avoid stressing the carbon in that area.