Two plausible reasons for some generic mappings not being created despite the SFTP job running are: A) the system reached its limit for the maximum number of generic mappings allowed, and C) there was an invalid format in one or more of the .csv files processed. When the maximum threshold for mappings is reached, the system cannot create additional mappings, thus stopping any further imports from being registered as custom objects. Additionally, if .csv files are incorrectly formatted, the job would fail to create mappings for those files, leading to the absence of corresponding custom objects in Business Manager. It's crucial to ensure that file formats adhere to expected specifications and that system limits are adequately managed to avoid such issues.