Can confirm that this still exists in PMS 1.24.5.5173 (using a Hauppauge Wintv-DualHD, Germany, DVB-C, Vodafone) and I agree with zeppel that this is hella annoying.
A response from the support staff letting us know if the issue is being worked on would be lovely.
There is another open thread on the exact same topic that has been neglected: Missing Channels during scan
