The Documentation Database is corrupted. We've seen this once before.
I can re-generate your DISK project (minus the 24 corrupted Nickname documentation records).
Q1. Does the DISK project match your current PLC Project (i.e. I can just "fix" the project you posted and that is good enough)?
About the corruption - we believe we have "fixed" what is causing the corruption, along with a better handling of existing corrupted documentation database records.
Back to your specific project to possibly understand the cause of the corruption - do you remember the element types associated with the following nicknames?
NN(RF1_1)
NN(RF1_2)
NN(RF1_1_ljos)
NN(RF1_2_ljos)
Q2. What were the elements?
Q3. Were there casts involved, or structures, or arrays, or

Please answer Q1, Q2, and Q3.