Looking at the logs, it seems that Data Preparation was unable to access some temporary files (namely the ones used to store the semantic types). Can you:
Check that the following folder exists: C:\Users\danm\AppData\Local\Temp\org.talend.dataquality.semantic\6334c248\luceneIdx\dictionary\default
Restart Data Preparation - or even better, reboot your machine - and try again?
That is quite unexpected. We just re-tested internally, and in case the folder gets removed, Data Preparation automatically recreates it with the appropriate content.
You will find attached the expected content of the folder, just unzip it in C:\Users\danm\AppData\Local\Temp and you should be able to access your datasets again. Note that the very first try could fail, but it should be back to normal on the second attempt.
Note that we changed the default location of the semantic types in the version 2.1.0 which will be released end of July (so in less than 2 weeks now). They're now stored in the Data Preparation installation folder by default, which prevents accidental removal when cleaning the temp folder.
