FASTA file with 50k+ sequences can't be opened as an alignment

1. Open any fasta file with 50k+ sequences (see an attachement)
2. Select: "Join into alignment"
3. The file can't be opened because there are more that 50k sequences (objects) in the loaded document.

The limit of 50k sequences comes from the Sequence Viewer and should not affect files to be opened in MSA Editor: in the alignment form the test file has only 1 object in the document.