I had a creaky BB30 BB on my new Cannondale Synapse a few years ago.
I tried everything with the BB30 brgs. Removal, re-installation, and using a special sealant. I spent a lot of time with the BB, and even contacted Cannondale, but the problem continued.
When I removed the chainrings from the crank, cleaned, lightly sanded the matting surfaces, greased and re-installed them the creaking disappeared; I used loctite 202, and torqued them to specs.
Whenever the creaking re-appears which happens after a year or two I follow the same procedure to eliminate the creaking. This procedure is always successful.