Activate Sauté (NORMAL) mode on the Instant Pot. Add butter into the pot to melt, then add the bacon. Sear it until it's slightly crisped, then transfer the it to a bowl with a slotted spoon; set it aside.
Generously season the beef chunks with sea salt and cracked pepper. Transfer them to the Instant Pot, about 3-5 chunks at a time (you don't want to overcrowd the pot), and sear them for about 4 minutes. Use tongs to rotate the beef so you can brown all sides. When done, transfer the beef to a plate and repeat with the rest of the beef until done.
Pop the pearl onions and mushrooms into the pot and simmer them, stirring occasionally, for about two minutes to soften them. Then add the garlic and simmer for another 30 seconds.
Pour the red wine into the pot, bring it to a low simmer, and deglaze the pan scraping the brown bits off the bottom and sides of the pot into the liquid. Continue the simmer for another 5 minutes.
Finally, add the beef broth, tomato paste, marinara, and beef base (I use Better than Bouillon paste, but you could also use a bouillon cube). Bring everything to a low simmer, stirring to ensure the tomato paste and beef base melt into the liquids.
Sprinkle in the flour into the pot and whisk it until it dissolves.
Add the cooked bacon and the carrots to the pot, then nestle in the beef, ensuring it's covered with sauce. Submerge the tied-up herbs and bay leaves into the liquid.
Cancel Sauté mode, then secure the lid onto the Instant Pot, locking it. Position the valve to SEAL, and cook on manual high pressure for 45 minutes. (Note: It can take up to 15 minutes for the pot to come to pressure and seal, so consider this when timing your meal).
When it's done, allow the pot to naturally release for 15 minutes. Then carefully move the valve to VENT for a quick release.
Remove the lid and activate Sauté (NORMAL) mode again. Leave everything to simmer for about 5-10 minutes to thicken up nicely. I like my gravy pretty thick, so I like to stir in a slurry at this point (2 TBSP all purpose flour or cornstarch dissolved in 1/4 cup cold water).
Taste the sauce and add more salt and pepper if needed; serve garnished with freshly chopped parsley.