This is stated on the corporate page on Twitter.

“A decision was made on the readiness of the Proton-M launch vehicle for refueling with components of fuel and launch, scheduled at 15:30:57 Moscow time on July 13,” the statement says.

# Spectrum: A meeting of the State Commission was held at the Baikonur cosmodrome - https://t.co/BF8lE3ybYg

A decision was made on the readiness of the Proton-M launch vehicle for refueling with fuel components and launch, scheduled at 15:30:57 Moscow time July 13 pic.twitter.com/CAQN2ED0uI

- ROSKOSMOS (@roscosmos) July 13, 2019

On June 21, it was reported that the launch of the Proton-M launch vehicle with the Spektr-RG space telescope from Baikonur was postponed due to identified observations.

The launch was postponed to July 13th.