Black areas through glass

Dear Blender enthusiasts, I have come here to seek your advice with the following problem:

Screen Shot 2020-04-21 at 17.30.21

Overlapping glass is being rendered black in cycles.
Increasing bounces has not helped.

Any thoughts ?

Thanks,
Tom

Increase the light bounces. If too little, the light rays would end early, turning to black as a result.

Thanks, I upped the bounces to 150 and no difference. Should I go even higher ?

Which bounces did you increase? You need to increase the transparency ones

I did. up to 150. nothng happens.

How about trying transmission instead? Will that fix it?

Try selecting full global illumination preset in the light path dropdown. If it works, bring down one at a time to say 4. If not, please share the scene.