Hello there.
Do the various streams that are being switched between contain the same FPS and key frame frequency across the set? Also, are the frame size, video and audio codecs the same for all the streams? Are they all H.264 video and AAC or MP3 audio?
If the codecs are not the same switching will be problematic.
Another problem could be that HTTP streaming sends chunks to the client. The client needs 3 chunks cached before it starts playing.
Does the HDS/HLS stream ever start to play after the switch? If so you could try modifying the default packetization settings.
By default Wowza is set to send 3, 10 second chunks in each packet sent to the client. You can modify this behavior by editing the Application.xml file.
This guide explains how to control how the Cupertino (iOS device) segmenter segments an incoming live stream:
How to configure Apple HTTP Live Streaming packetization (cupertinostreaming)
How to configure Adobe HDS packetization (sanjosestreaming)
I hope this is helpful in troubleshooting your issue.
Kind regards,
Salvadore