That sounds frustrating. I assume you're stock, no mods? The MHD app has pretty good code reading abilities, it's pretty good for monitoring and codes, even if you stay stock.
A lot of times I see people with long cranks end up solving it with a new low pressure fuel pressure regulator (opposite side of the tank as your LPFP). I'd recommend googling long cranking n55, or n55 fuel pressure regulator or similar to see how closely your symptoms match those guys. Let us know how it goes, and good luck!
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