HolographicDisplays version: v2.2.3-SNAPSHOT (latest Jenkins Build)
Spigot version: v1.14.4 (latest build)
Plugins:

I'm noticing that tamed horses keep disappearing on my Spigot server and I read that HolographicDisplays has previously caused these issues. Just wondering if there's any possibility that this is still the case.

Holographic Displays doesn's use horses since 1.8, it's definitely not its fault.