Sandbox receipt validation sometimes returns empty JSON response

When validating sandbox receipts (directly with Sandbox servers), I sometimes get a valid receipt back, other times empty response.
Issue is random, both outcomes can happen for the same encoded receipt from the iOS client. Empty response stops after some time.

I was wondering if anyone cam across this problem, and especially in Production? Perhaps, there is a way to prevent it from happening?

Will be grateful for any info on the matter.
Sandbox receipt validation sometimes returns empty JSON response
 
 
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