The whole point of this type of (partial) siphon drain is that it holds water high enough at the gravity drain point, so prime is maintained in the event of a power outage.
The weak link is when air bubbles accumulate at the top of the first bend. This problem is compounded when you can't see what's going on inside the pipes. I would add a 1" vinyl hose at the top, as it fits well over 3/4" hose. I would also install a one way air check valve so you can suck out the accumulated air with a venturi, aqualifter pump, or manually.
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