This may be a publisher or player channel issue, or keyframe issue.
Please clarify how do you publish a stream? What resolution and bitrate do you use?
Set the keyframe interval as we recommended in this post.
Try to check publish/playback channel quality: Publisher and player channel quality control
If the quality is BAD, try to use TCP for publishing/playback, use lower resolution/bitrate to conform the publisher/player channel.
You should adjust server settings as shown here Server configuration. Then, restart WCS, publish the stream from OBS and play it in Media Devices example (see Testing). You should see playback quality in Player section of the page.
If the quality is BAD, or if Nack count and Packets lost values are grow, try to switch to TCP transport
If this helps, set the transport at server side:
Note that this should be checked at the same PC where video playback is not starting in Embed Player.