Hi amartitegui,
I also encountered this problem and had a bit of a nightmare getting my anchoring right, setting below when they should have been above etc.
The way that worked for me was setting one main anchor and basing everything else off that anchor tended to work better. So BTN1 is the main anchor, then BTN2 below, set that to raBelow with BTN1 as the anchor, BTN3 to the right of BTN2 (raToRightOf/raAlignBaseline), with BTN2 as the anchor for BTN3. As you can see, base each anchor from BTN1, hope this makes sense. This could be an issue if you needed a button further away, but I would just use margins and +- away from the last anchor I needed. Not ideal but it works!
I found using more than one anchor independently resulted in the x and y going off the chart, so to speak.
You're not alone I have spent many hours on this
My LAMW app is here:
https://play.google.com/store/apps/details?id=swbcdx.cap.shortwavelistYou should be able to see my anchoring on the screenshots there.