From FT:
According to several HA executives, HA will still interline bags after May 1; however, the other airline segments must be on the same PNR. In addition, the connection between the interline partner must be within the "minimum connection time" and 4 hours. If the other airline segments are not on the same PNR and/or the time between connecting segments is longer than 4 hours, it's considered a "stopover" and you'll have to collect your bags and check them in on the other airline starting on May 1.
The "rationale" behind this policy change is three-fold. First, HA wants folks to use them for all of their travel needs to and from Hawaiʻi, considering that it has expanded its routes to Asia and the continental United States during the past few years. Second, HA can collect baggage fees from non-status passengers that don't have their HA flight segments on the same PNR as the other airline flight segments and/or "stopover" times in excess of 4 hours. And, third, HA doesn't want to be responsible if another airline mishandles a passenger's baggage