Inconsistent intervals when using large SDXC cards (256GB or above)

[justin-innonation]

Using an old A7S with high capacity SDXC cards (256Gb-1Tb tested, regardless of brand or speed) seems to cause inconsistent intervals (tested from 1s to 5s). The odd thing is that the regular PlayMemories Timelapse app seems to work just fine. However, the whole reason to use this app along with large storage is to take timelapses over a few days (weather related), with high-ISO sensitivity.

We have made a log and tracked that the intervals are all over the place, with actual interval differing between 90% to 1000% of the original setting value. Perhaps some calculations (capacity related) are made after the images are written to the SD card? Appears to some background processes hogging the timelapse flow.