Hi,

Are you sure the supply voltage goes to < 1 v when you re-apply power ???

Easy confirm :

1) Turn MCLR to ON AND Always let The Watchdog ON if no valuable reason to cancel it ( @ Sleep ...i.e.)

Code:
wdt_off, MCLR_off
I'm not not kidding, here ... but ... I could !!!

2) enable the Brownout function ...

3) Allow the Power-up Timer ...

4) use a R/C/D reset circuit instead of a simple resistor ( Datasheet $15.2 )

Alain