What can be the reason of such delay?
Fee per weight unit 11.500 sat/WU
While you paid "46 sat/Byte"... because it's using legacy inputs/outputs... your transaction fee is only 11.5 sats/Weight Unit... and this is what has been happening on the network in recent hours:
Even given the relatively high fee, you're still several blocks worth of transactions from the tip:
Blockchair is calculating your "priority" as 14031...
Once, things settle down, the transaction should confirm... or you can try using RBF ("Replace-by-Fee") to increase the fee as your transaction appears to be RBF-enabled and you are using Electrum.