Storyline slide view on iPAD does not work

I have imported a bunch  of slides form a Powerpoint presentation in a storyline new project . everything goes well on formatting all the slides and distributing them in logical way based on subject covered(in Powerpoint they were just one following the other presentation way).

I published the project with no failure at all and checked the Html5 output for its usage on iPAD. I loaded into our LMS and worked perfectly when run using personal computer. But when the course is ran on iPAD the first two slides work as expected.

When from main menu user select the first course slide using the iPAD then the slide shown is full blank with all the basic controls in view(prev/next button repeat, seekbar, title etc.) and working. The ssek bar goes in progress for the time the slide last (5 seconds more o less) then it stops but the slide is still blank. Now if a select the repeat then magically the slide come in view and contents is shown as expected. This beahviour is for all the slides of the project with the exceptio of final questionnaire (this part was not from the Powerpoint but it was created ad hoc in the storyline course). It seems to me that the slides when started are put in a sort of "standby state" awaiting for some input.

So when user try to repeat the slide the "standby state" will terminate and slide works.

I tried to change all the possible setting including moving slides form one project to another with no success. I double checked and there are no visible triggers controlling the slide and the text or image iitial state is all normal.

I have no other ideas on my mind and asking for some help on solving the issue.