1. Appendix is not included in the table of contents: you may not have added the contents of the appendix to the table of contents when writing your paper. If the appendix content is not in the directory, then the appendix page will naturally not be displayed in the generated directory.

2. Appendix format: The format of the appendix may not meet the requirements of the paper. Please check the format of the appendices to ensure that they are consistent with the format of the body and the table of contents.

3. Too many appendices: If there are too many appendices, the table of contents may be too long. In this case, you can consider splitting the appendix into several parts and adding them to the directory respectively.

4. Incomplete appendix: If the appendix is incomplete, there may be no appendix page in the catalog. Please ensure that the appendix is complete and add it to the table of contents.

5. Directory generation problem: If you use the tool of automatically generating directories, the generated directories may be incomplete. In this case, you can manually check the table of contents and add the missing appendix pages to the table of contents.

To solve this problem, you can try the following methods:

1. Check the appendix: ensure that the appendix is complete and meets the requirements of the paper.

2. Adjust the appendix format: ensure that the appendix format is consistent with the text and directory format.

3. Split the appendix content: split the appendix content into multiple parts and add them to the directory respectively.

4. Manually add the appendix page: manually add the missing appendix page to the directory.

5. Check the directory generation tool: ensure that the directory generation tool used works normally, and check whether the generated directory is complete.