SD card gets frequently "unexpectedly" disconnected

[xarx00]

At the beginning of this year I've bought 2 pieces of new LG D620R G2 Mini (from different e-shops). Both have the same problems with (micro)SD cards:
About once in an hour, the phone reports that the SD card was "unexpectedly disconnected". Sometimes it connects it immediately back again, but most often (90% cases) the phone restart is necessary. Mechanical removal/insertion of the card does not help. The phone restart fixes the problem for the moment.

So, as both phones have the same problem, it would seem that the problem is at the side of the SD card. But I have another SD card (same type but bought a year ago), and the phones exhibit exactly the same problem with it. Both cards work fine in a HTC phone and in a SD card reader. I have also tested another SD card, and neither phone is able even to read it (they say the card has invalid format), though the card works fine in the SD card reader (and is FAT32 formatted).

In summary:
I have two phones, 3 cards, and none combination is working.
2x LG D620R G2 Mini, one from Poland, the second one from France, both new and bought at the beginning of this year.
2x Kingston Micro SDHC 16GB Class 10 UHS-I (with golden print)
1x Kingston Micro SDHC 16GB Class 10 (with white print)

What may be the problem? I was consulting with LG support, and they say there's no known problem of the G2 mini phones of this kind. And they suggest me to bring the phones to a repair shop (which would mean that I wouldn't see the phones for at least a month).
Should I return the phones? Should I bring them to a repair shop? Should I try another microSD card (I would have to buy it)? What would you suggest in this situation so that I won't lose even more time and money?

 

[B. Diddy]

Welcome to Android Central! Where did you purchase your SD cards? If you got them online from the some random store, it's possible they're counterfeit, and therefore more likely to be problematic. The SD Insight app can tell you if a card is what it says it is.

Assuming the cards are legit, Kingston should be relatively reliable. However, it may be worth trying a Sandisk card, which many regard as the best.

 

[xarx00]

SD Insight says that the origin of the (two UHS-I) SD cards is unknown. However, I'm almost sure they are genuine as they were bought in a big renown IT shop.

I can try various SD card brands one by one till I find one that works with the phones. But that experiment would cost me money, which I would like to avoid. Are you sure the problem is in the mutual incompatibility? Currently I found no (micro)SD card that would work with the phones. Couldn't be the problem in the whole serie of the G2? (I know, it sounds improbable. )

 

[B. Diddy]

The only one I'd probably try would be a Sandisk. If that doesn't work, I'd suspect a problem with your specific device, not with the whole line. Perhaps there's a problem with the SD slot itself (i.e., the contacts).

 

[xarx00]

Yes, I suspect the SD slot too. However, I wonder why would the same problem be on two different devices? Visually, there seems nothing to be bent in the slot.
If I bring it to a repair shop, I suspect that after 30 days (determined by law in my country) they would return me the phone unfixed anyway with the explanation that they were unable to reproduce the problem.

P.S. Thanks for the suggestion of SanDisk.

 

[B. Diddy]

I think I may have missed the fact that the issue is occurring with two different devices. That does make it less likely to be an SD slot issue, unless it's a common defect in that model.

 

[xarx00]

I've bought a 32GB SanDisk SD card. Though the disconnection doesn't happen so often now, it still happens sometimes. This usually happens when starting an application that needs to work with the SD card (like a music player), but if it's not a SW problem, it may be that the card had been already disconnected and the OS discovers that only in that moment. It suffices to reconnect the SD card again (Settings>General>Storage>ConnectSDCard), and everything works again.

So, the problems persists, though the severity is lower now..