Aegean Miles+Bonus Silver/Gold status is very difficult to retain if you fly mixed Star Alliance.

I live in a European capital outside Greece and fly Aegean 4 times per year (2 round-trips) give or take.
I fly maybe another 4-6 flights per year to destinations within Europe not available by Aegean from my city of residence.

I am always paying premium to fly with Star Alliance, in order to retain my Aegean Miles+Bonus frequent flyer status. But most times I get zero miles from Aegean for the flights with other companies. I have tried all: cheap fares, "eco" fares, flex fares, even business sometimes fail to qualify for Miles in Aegean Miles+Bonus.

It is clearly stated in the terms of Miles+Bonus that only some ticket classes qualify. For example see here:
en.aegeanair.com/milesandbonus/partners/airlines/lufthansa/
However my point with this post is to highlight how frustrating and time consuming it is to book a trip that qualifies for Aegean Miles+Bonus points.
For example I was trying to book one such trip with Lufthansa (EDIT: Brussels, I just checked again), and if I recall correctly all ticket choices were showing a non-qualifying fare (even business class was showing class P).
And one can not use a 3rd party booking service (like expedia) to make life easier, because then the booking class is not shown at all.

Any advice to give? How do you book your flights? Do you suggest some other Star Alliance bonus program that is much easier to retain when flying with many companies? Or should I give up completely on booking exclusively Star Alliance?

Thank you in advance.