Thanks to everyone who has reported this issue! As DMXIS and its accompanying configuration software has long been discontinued by Enttec, we are unfortunately unable to continue to provide official support for this device.
While several users have now observed this problem, we haven’t been able to reproduce it with our DMXIS unit on several computers, which prevents us from investigating this any further.
We recommend getting an Enttec DMX USB Pro or an Art-Net node instead.
Still, there are a number of DMXIS devices in circulation and it would be nice and planet-friendly to have a fix for this. If you are experiencing this issue, you are welcome to send us your unit and we will have another look. You can get in touch about this via support@showsync.com.