There are 2 different concepts in regards to SAS Date/Time values:
1) How the number is DISPLAYed (using a SAS FORMAT) and,
2) how the number is INPUT -- if you are using SAS to perform data entry or reading data INTO a SAS dataset, then you must use a SAS INFORMAT.
What can be confusing is that the names of the FORMATs and INFORMATs can be the same. And just because you have a SAS FORMAT for display does not mean that you have a SAS INFORMAT for entering data via SAS.
Suppose for, example, that a person's birthdate is Nov 15, 1950. The "internal" value for that SAS date value is -3334. I can DISPLAY that number with the date9. FORMAT and then the DISPLAYed valued would be: 15NOV1950. If I wanted to perform data entry into a SAS dataset, without an INFORMAT, I would have to enter that date as -3334. If I had an INFORMAT of MMDDYY10., then I could type 11/15/1950 into a cell. If I had an INFORMAT of DATE9., then I could type 15NOV1950 into the cell.
Most times, folks don't worry about setting an INFORMAT because they're not doing "data entry" or they're not reading "raw data" into SAS such that they need an INFORMAT. However, you might check your table settings to make sure that both a FORMAT and an INFORMAT have been set for your dataset.
If you need more help using DIStudio or setting INFORMATS, you might consider contacting Tech Support.
I reproduced your problem, and it seems like a bug to me. My Time8. formatted fiels are displayed as a datetime value, and it does not accept any time or datetime values I tried out. I suggest that you report this to tech support.