This may be similar to, or related to, Bug 382412. I have two Fedora 27 systems, both running: kdeconnectd-1.3.0-1.fc27.x86_64 vlc-3.0.3-2.fc27.x86_64 One works; one doesn't quite work properly. It will pause, skip 10s etc, but the play button on the phone under Multimedia control does not work. It is not coloured orange as it should be. All the other functions seem to work. Thanks for this otherwise great software :)
This is a VLC bug, sorry :( All other mpris controls (e.g. taskbar right-click, taskbar window previews, media control applet) have the same issue. I can't find the link anymore where I read about this anymore, so you might want to submit a bug report to VLC.
I have the same problem with the play button. However, the problem only occurs on my Android 6 tablet. On my phone, which has Android 8, the play button works normally. (Both tablet and phone have kdeconnect version 1.8.4; my laptop has kdeconnect version 1.3.1-0ubuntu0.1)