Hi,
I've seen the problem when used in combination with Required Insurance.
eBay apparently can't "calculate" the amount on the basis of 1st Class International doesn't qualify (in eBay-think) for USPS postal insurance.
Solution: Use the Handling charge to add-on the Insurance for Required and use "Included in S&H" on the Insurance line for the one-page. That worked for the test case I did with a member, and the rate then appears as normal in the shipping table.
I don't know if a similar problem occurs for optional insurance.
Danno