Alpha in Compound or fusion clips not working

I have been testing Resolve 15 beta 4. The recent release notes mentioned: “Addressed an issue with alpha handling for Compound clips and Fusion clips”.
However I still get an issue with alpha for Compound clips and Fusion clips. For instance, if I create a Compound clip or a Fusion clip from one single PNG with a transparent background, the alpha works fine, and I can still see any content on the tracks below… but if I create a Compound clip or a Fusion clip from two or more stacked PNGs with transparent backgrounds, the background becomes black and it covers all of the bellow tracks showing no alpha or transparency at all.
Could you please help me with this?
Thank you.
However I still get an issue with alpha for Compound clips and Fusion clips. For instance, if I create a Compound clip or a Fusion clip from one single PNG with a transparent background, the alpha works fine, and I can still see any content on the tracks below… but if I create a Compound clip or a Fusion clip from two or more stacked PNGs with transparent backgrounds, the background becomes black and it covers all of the bellow tracks showing no alpha or transparency at all.
Could you please help me with this?
Thank you.