I was at ds9 i left ds9 and in orbit map of ds9 (before sector space) then i had click on transwarp to sb. Worked fine. Did a little but of walking in sb then i beamed out to go join a friend on tholian map. When i click on the beam out of sb icon the same as transwarp etc (cant recall if i left sb and was in sb orbit map or on the sb still at the time). I was back at ds9 not outside of the sb so i could easily go to tholian planet.
I expect when i click leave sb to be in eti erandi sector not ds9.
While I agree with your expectations that it should drop you in Eta Eridani, the warp to starbase power is currently designed to return you to your previous location. You must use the starbase trainswarp gateway to change your location.