try deleting the cache folder then restart Legacy Studio. to do this
1. press Win+R to open the Run Command box
2. type %APPDATA% then press enter
3. you will be redirected to the roaming profile folder
4. on said folder, locate and delete ALL folders that start with SignageStudio - there are two of these
5. after deleting the folders, restart studio and try again
best regards
-ADMIN