I'm assuming it's the facelift version - therefore I have an idea about your problem, but no solution...
As most of you know, Octavia 4 has a few other siblings - the Golf 8, the Formentor and the latest Leon; as such, they share lots of stuff... mechanically, electronics and as a consequence - problems!
A few months ago I was discussing with my Cupra dealership as they were just receiving the first transport of facelift Formentors. He was telling me that when they washed the cars after the trip from Spain to Bucharest, about half of the 10 cars they received didn't start... They immediately scanned for errors - nothing stored!!! However, after closing the cars and waiting for a couple of minutes they start without any issue... 😇
On the other hand, over the past several months, on the Formentor online group we use here in RO to share useful information/solutions/tips, quite a few of those with the facelift model mentioned that their cars didn't start on few occasions, either after washing the car, or after rain overnight, even after heavy-fog... high-humidity being the common denominator. In ALL cases the car started without problem after some waiting time with the car locked.
Since the problem you described in your first post reminded me of all the situations that I mentioned above, am I wrong to assume that on those mornings when you encountered the problem the outside humidity was high?
Apparently there's no formal solution from VAG, no TPI... but it's already quite well known unfortunately. I even found online the same problem (and "solution") mentioned for the new Tiguan; they were mentioning some communication issues caused by the Gateway, but until there's an official answer from VAG - it's all just assumptions.