Interestingly, I just called support over this same issue.  IDR is rejecting all of my Indiana returns claiming the PTET (where you are required to attach a pdf of the K-1 to show the PTET paid by the PTE).  I called IDR and they said they have allowed pdf attachments for years.  

I called Lacerte support and they said, even though the program includes the option to "Send pdf with Indiana return", they don't actually send the pdf attachment to Indiana because "Indiana doesn't accept pdf attachments", per the support agent.  This is patently false.  

Lacerte needs to fix this issue or they are going to have a lot of Indiana practitioners leave for other software.  I am now having to respond to dozens of rejection notices from IDR and will be required to spend tons of my time in the summer fixing this.  I will also now have to file all these IN returns by paper going forward if I stay with Lacerte.  This is UNACCEPTABLE.  

It's also unacceptable for Lacerte support to continue to say that IN does not accept pdf files as attachments.  They do.  Lacerte just can't do what it's supposed to do.