is there a limit to how many manual entries you can put in a Combo?

I've just tried creating a drop down list Combo with 17 choices and 3 columns.

The builder (Combo Box) lets me build it but when I run it, all choices after number 9 have disappeared and the text is truncated half way through the middle column of the ninth choice!

Is this normal?

Is there a fix?

Thanks

Harry