Hi,
I have the occasional glitch like that but with an ESS.
I came to the conclusion it was akin to Run-out-of-Data. The ESS does alert you that is the case....but that warning can be suppressed also.
I assumed that I had suppressed to warning but was a fault of that nature.
A few months ago the problem became more persistent, even troublesome. Then I recalled my PC had not been turned off for about four months.
I shut the PC down, rebooted and the problem has gone away...almost. I make it a habit now to shut down the PC every month or so.
Craig