A LA marketed and DL operated flight will not earn with AS.
From alaskaair.com:
To qualify, flights must be within the LATAM Airlines flight number range (LA) 1–805, 808–4799, or 7500–8299, and be marketed and operated by LATAM Airlines. The two-letter airline code (LA) must precede the flight number (for example, LA XXXX) on your ticket receipt or boarding pass.