32Gb Class 10 sd card wake problem

[N9700]

First post here and new to smartphones. I have a Star N9700 quad core 1.3GHz 5" screen. Ok, its a Chinese phone but it works very well except one problem.

I bought an Integral 32Gb class 10 micro sd card. I have confirmed it is genuine and it works fine on my laptop and passes h2testw.

However, most of the time when the phone goes to standby (screen off) and wakes up again, all the files on the sd card are "unavailable".

I have seen many posts of cards being unmounted but in my case, the phone thinks it it still mounted but the files unavailable (e.g. in file manager or music players). If I unmount and remount, it tells me the card is damaged but rebooting the phone, everything works again.

If listening to music with PowerAmp after about a minute the track will start skipping, playing just the first second of each track and then eventually say "too many errors".

I have the opportunity to return the card but

1) Is it just faulty and a replacement will be fine. (the supplier may be unhappy if they cannot reproduce the fault)
2) The phone somehow does not like the brand and I need to switch manufacturers.
3) Are 32Gb Class 10 generally ok with current smartphones running Android 4.2.2?
4) Is there a (software) solution for it?
5) Are there any known issues with Integral?

I have reformatted (full) the card, made sure there are no power saving apps, even ran the Wake Lock app, made no difference. I have two other 8Gb cards and they both work fine.

Thanks.

 

[Crashdamage]

I would bet heavily that the problem is the phone and not the card

 

[N9700]

I would bet heavily that the problem is the phone and not the card

You could be right of course but as my 8gb cards work fine, how do I know what will work and what wont? i.e. is it the class 10, the size the brand?

I have read many posts of the similar issues. i.e. sd card unmounting after screen lock, in all sorts of different phones and manufacturers of cards and different versions of Android. This would appear to be a very similar problem to mine. Although in my case it does not say "card unmounted". Just that the files are not available. If I unmount and remount the card (in the phone) it then says "damaged card" and offers to format it but it cannot do it. Just rebooting and everything works until the screen locks again.

I did read a suggestion to ensure "keep wifi active in stanby" and that seems to keep the sd card active for longer and even then, after a few minutes max, the files are again not available, or the phone locks up.

Integral have been great so far and have supplied a replacement card but that does the same. They have offered a class 6 instead but how do I know if that will work, other than trying?

Such a shame that there seem to be so many people having what seems like the same problem but no real solution?

Would be nice to know what others with the same phone are using but I guess there are not too many people with these yet? I have seen that other are using 32gb class 10 but not which ones.