Can't conitunue edit PDF in Impress after export

I successfully edit my PDF via Impress(LibO 4.0), export and open them more than 10 times, but now it crashes impress when trying to open. What it may be?

Do you remember what you did last before opening the file makes LibreOffice crash?

Are you sure it is Impress?, LibreOffice edits pdfs with Draw.

I try to open my PDF in Draw now. Draw crashed.