I don't have a solution, but apparently Adobe are using "Adobe Air" in ADE which doesn't support Arabic just like few other Adobe mobile applications, so unless Adobe switch to HTML 5 your readers will not be able read Arabic just like you experienced.
I have the Same problem in Arabic, I read to someone here in the forum says that he contacted the Adobe support and they answered him that the RTL composer is not fully supported in EPUB.
Actually I do not know what should we do in this case, Any one can help ?
EPUB is not an Adobe product, we were discussing here Adobe Digital Edition which fails to display Arabic well. Having said that EPUB format displays Arabic well and there are quite alot of Arabic publications in EPUB format, just use EPUB reader other than ADE.
What are you using to put your Arabic publication together? Did you try InDesign?
Here is an Arabic publication in EPUB format with search successfully finding word in the e-book. I'm using Apple's iBooks app on iPad.
Hey, I discovered something i want to share with you. I had the same problem Arabic is not displaying well
At first, you have to be 100% sure that your INDD file is not contains any overrides at all
Then if you export you epub as version 3.0 test it on and IOS or android device this version well be corrupted on windows at most cases.
if you want to check your epub on windows export it as version 2.0.1
it displays well with me, actually not 100% fine but it is great result for now to me.