I've "always" had problems with SD cards on Arduinos, going back for years. Arduinos and Teensy run the same libraries. And even though Bill Greiman has been working on the libraries constantly. Some of the exact same errors have occurred going back to 2012 or so.
Some of these issues were discussed on recent threads I participated in. Even running the latest libraries, I consistently have the problem that I write the card using the Teensy, but then when trying to read the cards on my Win7 or Win10 laptops, they say there is some error on the card that needs "fixing". Sometimes I get FILECHECK errors after writing, eg these are on the card I am currently using in the T3.6 dedicated slot:
> FOUND.000/
> FILE0000.CHK 2326528
> FOUND.001/
> FILE0000.CHK 32768
> FILE0001.CHK 32768
> FILE0002.CHK 32768
Greiman has always recommended:
1. format using SDformatter, and NOT Windows.
2. making sure you don't have a counterfeit knockoff card, usually shown by the FAT listing.
Further, from my experiences, I'd say,
3. NEVER EVER NEVER plug an SD card into an Arduino/Teensy that has
important data on it; use only dedicated cards that are not used for anything else.
4. don't try to run SD cards on the same SPI port with
anything else, like LCDs or other SPI devices, it's a bag of endless conflicts.
5. if you buy any of those little SD Card modules from ebay/etc, note that some of them have smt Rs to interface to the uC, and some of them have a chip; the ones with the chip will not release the MISO pin.
EDIT: there is one other issue to mention,
6. this shouldn't be a problem with the T3.5,3.6 SD slot, but in regards item 4 sharing the SPI buss, SD cards do not automatically release the MISO pin; there was a discussion of this a couple of years ago on the Arduino forum. The apparent solution turned out to be [IIRC] to send a few clock pulses to the SD Card "after" SD-CS is de-asserted, and before CS on any other device is asserted. I recall Bill Greiman saying he had incorporated this fixx into his libraries. I don't know about other libraries.
OK, so these are just some of my own suggestions, and you're always free to do what you want of course,
. There are ways around the issue of item 4, but it may take some work.