It seems like everytime you find either a ruined portal or a bastion remnant, the chests generate with no loot inside them whatsoever. This applies to both already created and newly created worlds.
Nether fortresses are not affected by this bug for some reason, neither do the Overworld structures such as villages and desert temples.
Thank you for your report!
We're actually already tracking this issue at MCPE-69003 and MCPE-79434, so I will resolve and link this ticket as a duplicate.
If you would like to add a vote and any extra information to the main tickets it would be appreciated.
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