get_symbology() from SEDOL to RIC returns "no best match available"

I am trying to convert SEDOL to RIC through get_symbology, but it returns "no best match available". Meanwhile, Same SEDOL is able to convert SEDOL to ISIN.

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However, I tested it with other SEDOL, it is able to convert SEDOL to RIC.

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Those unavailable assets are mainly ETFs, and I wonder is this the reason that cause the issue, thank you.