Odd failure, , engine does not start, not DTCs

Today my car did not start - 2016 Golf sportwagen TDI 2.0

It cranks fine, it start to fire , but then dies

Checked with VCDS, no Dtcs were stored
battery voltaje 12.4 v

Fuel tank almost full

Since I do not move it often since mid march, it started to develop a long crank in the mornings, like 5 seconds or so

It sounded as it did not have enough fuel to startup

checked the diesel filter, the deposit was full, closed it

tried again and it fired up, like nothing is wrong

I'm going to replace the diesel filter, I replaced it maybe 15,000kms ago

any suggestions on what else to check ?

Mine just did it but had lots of lights turn on and loss of power. Waiting on tow.

i'd toss a battery tender on it and let it cook for 3-4 hours.

thanks

battery is on life support as I write this