Just to set the record straight, there is at least one cheap (made in China) MIDI/USB connector that regularly causes problems. There seem to be some serious design problems. If you check on the web, you will find references to this, even discussion about 'repairing' it.

This sort of device should be avoided, just not worth the trouble.

There are however better made devices, maybe not from China, certainly more expensive, and these can work perfectly OK.

Basically, you get what you pay for!