What can cause no PAG oil recovered by machine?

We are a small shop, just added a recovery machine (and 609 trained) for customers. A 97 suv was serviced recently. Normally holds 3 lbs, machine recovered 2.8 lbs of R134a. But only a small trickle of PAG oil came out of the recovery machines built-in oil separator (< 0.1 oz). This is not what we would expect, but then we are new to this line of work. System holds good vacuum after installing a new OEM hose assembly. Leak was easy to identify as customers vehicle had dye installed from compressor replacement done 4 years earlier elsewhere.

Would so little pag oil recovered from 2.8 lbs of refrigerant be expected with a long term but seemingly small leak in the high side hose assembly?