Flight Plan wrong airways

Hello,

While trying to plan a flight from LGSM to LTCS with the Kodiak at FL190, the generated route came as follows:

SAM OKESA T283 KAVAK T489 AKIMO UW89 AYT UR55 MUT UW74 GAZ UW716 LUTAM

Given that some of those airways (UW89, UR55, UW74 and UW716) have a minimum altitude of FL285, why does SB suggest them for a flight cruising at FL190 (Kodiak ceiling is FL250)?
Even more: if I don’t manually select my desired cruise level, SB plans the flight at FL070 with the same airways. Why does it calculate that altitude when the MORA at many waypoints is 90, 95 and some even 105 (and by the Navigraph enroute charts some sectors along the route even go to MORA 130, 150 and 158).