Batch-renaming XAVC files is not possible in MC. These files have to be renamed in advance outside of MC.
Up to MC 8.5x the Sony Plug-in PDZK-MA2 was used to link XAVC files in MC. This plug-in worked well with XAVC files which were batch-renamed before linking them in MC.
With MC 8.6 however, the plug-in MVP_MSP_SonyXDCAM_64-bit is used, linking to XAVC files which were batch-renamed before linking is no longer possible. Each batch of files have now clips 0001, 0002, etc. That means you get multiple clips with identical names in a progressing project.
Working with these clips is confusing and dangerous (e.g. if you want to delete clips). Renaming each individual clip separately is painful.
As long as batch-rename is not possible in MC 8.6, I probably can no longer film in XAVC but am restrained to film in AVCHD (AVCHD files can be directly imported into MC 8.6, no linking is necessary).