How large is your composter? Many of the "bio-plastics" require high heat composting to decompose, and even then may require a large amount of time. Unless you've got a massive compost pile with adequate aeration and turning, almost no bio-plastics will truly decompose at home.

From the EPA[0]:

> If a plastic product is labeled “compostable,” can I add it to my home compost pile?

> No. Unless the label indicates that the product is okay for home composting, you should not try to compost it at home. Plastic that is labeled as compostable is generally intended to be sent to an industrial or commercial composting facility which has higher temperatures and different breakdown conditions than those found in a typical homeowner’s compost bin. If your community has a residential compost collection program, check with your local government or recycling company to find out if they will accept compostable plastic under this program.

[0] https://www.epa.gov/trash-free-waters/frequently-asked-quest...