beef barbacoa instant pot fail

Dear fellow culinary conspirators, I planned to serve a mess of slow cooked beef barbacoa tacos for my son's high school grad party tonight. I;ve made this a dozen times and its always been amazing. Used 9.5 hours at "low" function on instant pot slow cook + 50 minutes ( keep warm) - had some errands this am.
Used a 3kg oven round roast and the meat was completely submerged beef broth. I've never used as large a roast
THe meat still seems really tough and not shredding properly though tastes great. I read somewhere that meat has to get to an internal temp of 160F to get tender enough to shred. THe temp of the roast was 150F and 133F ( had to cut it to make it fit, though it had been in sitting in the "keep warm" temp). Its cooked all the way though
I was thinking I would put it in for another hour at the "normal" slow cook setting. Any thoughts on rescuing the meat - cheers

this is the recipe I use:



SillyBee June 14, 2020
I've read that meat's connective tissue has to dissolve in order to shred properly. The most effective way is long, slow heat or a pressure cooker. It sounds like the meat was cooked through but just not cooked long enough to dissolve the connective tissue. Because the roast was much bigger, it probably takes much more time. The recommendation to finish it in pressure cooker mode should do the trick.
HalfPint June 12, 2020
Try cooking for ~35 minutes on the Pressure cook function. If that doesn't tenderize, I would thinly slice the meat across the grain and serve that way.
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