Update RSDN-20 13 May 2018

They are again off air at least since Yesterday: no signals during last 24h, I have checked various times along the day.
As a conclusion - for the time being - I would say: they have been off air for months, they turned on for 3 days and now off again. It's not a matter of bad band conditions of course since the Beta Time stations are received with strong signals, even RJH66 from Kyrgizstan.

On the Twente Web SDR no signal as well,

I can only suggest: stay tuned.