There are several occassions where users would like to render pages on iFrames via SuiteScript, where the field type is set to inlinehtml. It was observed though that there are instances when such use case resulted to blank iFrames.
The reason behind such behavior is due to the new implentation across many modern browsers called "Mixed Content Blocking". Having such feature, one should not mix secure content ("https" source) with insecure content ("http" source).
It is important to note though that for Firefox 23, it is the Mixed Active Content requests that are being blocked.
To find out more regarding the Mixed Content Blocking feature in Firefox, one may refer to the following link: