I looked a bit more closely and actually found your corpus on arkindex.teklia.com (ID bda6ab9e-22f7-...)
I reproduce the issue you are facing when trying to import the whole corpus into a new empty Callico project (the arkindex instance is unable to list all the elements, even with a pagination, as the project is large).
Limiting the import to page + text line does seem to help a bit.
What are your goals for that import ? Importing every annotation produced by Machine Learning to validate them ?