Does anybody has this issue with eosm and lexar or other cards? Thanks for answers!
There are not that much solid informations and/or serious reviews about this card available on the net (and definitely not here). My most trusted source is
www.cameramemoryspeed.com for this matter. They run cards in various cardreaders and in some cams.
Your card is an UHS-II card running in UHS-I compatibility mode when inserted in EOS M. There were issues with early UHS-II cards in compatibility mode (slow speed) but this should be history (only guessing, of course).
And there was a single card type once giving good results with cardreaders and most cams but had serious speed issues with some Canon cams only.
If you have a decent cardreader without UHS-II interface (Kingston FCR-HS3 for example) you may have some benchmark runs with CrystalDiskMark (Windows) or Blackmagic Disk Speed Test (macOS).
And run benchmark in cam
1. Modules tab. Activate bench.mo
2. Restart cam
3. Access Debug tab -> Benchmarks -> Card Benchmarks -> Quick R/W benchmark (1 min)
Sandisk Extreme Pro 95 MB/s is considered to be "gold standard" by ML users. Never heard any complaints (apart from faked cards). Newer 170 MB/s variety seems to be a safe card, too.