If you downgraded your GTA V version or installed a large mod pack (e.g., NaturalVision, VanillaWorks), the mpchristmas2017 folder may be corrupt or deleted. The game does not crash without it (because it’s an add-on), but specific Christmas cars will appear as missing or invisible.
Released on December 19, 2017, this DLC was the fifth annual holiday event for GTA Online. Unlike major updates that require massive downloads, much of this content was toggled via "tunables," though the core assets—models, textures, and scripts—remain stored within the mpchristmas2017 dlcpack. Update X64 Dlcpacks Mpchristmas2017 Dlc.rpf