Invisible text entry field on iPad when Show Text Box Frame is deselected

Hi.

I was hoping someone may have a solution to an issue I am experiencing with Captivate 9. When I deselect the 'Show Text Box Frame' option on a text entry field, the text is invisible. The field operates OK, but you can't see the text. This seems to be specific to iOS and happens on both safari and chrome. It works OK on other devices including android.

Thanks in advance!

Louise