It's a font issue. I know, duh! Call me captain obvious.
Are you using a TWS template or starting from a new file within Finale 27? New files within Finale 27 use the new SMuFL format. This confuses Finale if you were to load the Percussion Library that is included with the template package. Only option here is to start fresh with a template file.
If you are working from a template file then something has altered the font choice for percussion notation. I'll need to check Finale to verify which font is the default for Finale 2014.5 - 26. If you have Finale 26 installed open a template file in FIN26 and see if the font issue is still messed up.
Finale 2014.5 - 26 this path open a template file then Document > Document Options > Fonts > Notation > from Notation drop down list select Percussion Noteheads > (default is) Maestro Percussion 24.