I have tested this issue on both the Nintendo Switch version of Bedrock and the Android version and the results are the same. On any worlds generated in 1.17.10 with the Caves and Cliffs experimental toggle enabled, bonus chests will not generate. There is a possibility they could be generating deep underground or much farther from spawn but I cannot confirm this.
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We're tracking this issue in MCPE-125872, so this ticket is being resolved and linked as a duplicate.
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