Getting css name collision when all class names are different

Hello, I am exporting a book to EPUB. Before I did so I opened the style source document and ensured that all paragraph styles had a unique class name under "export tagging". Then I synchronized the book and tried to export it to EPUB. I keep getting this error:

CSS name collision : 88 detected.

Paragraph Style "Chapter Subtitle" and "Chapter Title" generate conflict css name "ch"

Paragraph Style "Chapter Title" and "Chapter Subtitle" generate conflict css name "ch"

Paragraph Style "Paragraph - Beginning" and "Paragraph - First" generate conflict css name "p"

Paragraph Style "Paragraph - First" and "Paragraph - Beginning" generate conflict css name "p"

Paragraph Style "Paragraph - Last" and "Paragraph - Beginning" generate conflict css name "p"

Paragraph Style "Paragraph - Next" and "Paragraph - Beginning" generate conflict css name "p"

Paragraph Style "Paragraph - Only" and "Paragraph - Beginning" generate conflict css name "p"

Paragraph Style "Title Page - Author" and "Title Page - Title" generate conflict css name "title-p"

I went through every single individual document and verified that there are no duplicate or blank class names. I can't for the life of me figure out why I keep getting this error.

Any help would be appreciated.

EDIT 1: more information below.

I looked at the exported EPUB in Calibre and all of my styles beginning with "paragraph" (e.g. "Paragraph - Beginning", "Paragraph - First", "Paragraph - Last", etc.) have the appearance in the EPUB reader of "Paragraph - Beginning". Something very strange is going on here, InDesign is not respecting my style definitions at export.

EDIT 2: I discovered a workaround.

If I do the following, I can get this EPUB exported without error:

1) Open the first document in the book.

2) Export the single document as an EPUB — it will generate the error.

3) Export it again with no change — it will export with no error.

4) Repeat the process for each individual document in the book.

5) Export the whole book at the end.

Clearly something is going wrong here, this is not really a fix but a workaround to some sort of bug or corruption.