Could be a channel issue based on the country setting. You might want to try to install cdra and set your country manually.
Generally in this cases I suggest to install wavemon to monitor the signal strength as one problem is that OSMC switches to scanning if the signal falls below a certain level.
You also can try to disable background scanning, see this thread
Could be a power issue. Do you have other USB devices connected? What powersupply are you using?