Hi Sarah,
I've no enough experience with different mobile devices but it sounds like an issue between your device and the SCORM API engine implementation in Moodle.
If the two content versions shares the same kind of data - here I guess interactions - I cannot understand the reason why you need to expand the size of CMIString4096 unless linked to an issue to support some regexps at your mobile device side.
Have you tried with a different mobile device or using a newer Moodle version e.g. http://demo.moodle.net/ (for a better mobile friendly ecosystem)?
HTH,
Matteo