Having a hard time discovering/utilizing a chromecast in a network with multiple APs

I have two APs in my network; a primary router and a secondary AP which is meshed using 802.11s (currently meshing over two networks, both bgn 2.4 GHz and nac 5 GHz.)

I'm seeing some difficulty in discovering/connecting to/casting, more specifically it seems to be more problematic when my casting device (e.g. a phone) is connected to one AP and the chromecast is connected to the other.

I have read that LEDE can need to have IGMP snooping/Multicast Forwarding set up to support things like DLNA, UPnP, etc. Is this along the lines of the difficulty I'm having with my chromecast?

I'm hoping for some advice on how one might improve the situation when meshed. With a single AP (primary router, no mesh AP), there's no problems whatsoever.