Showing incorrect label names in mashup design (9.0)

Hello Team,

I have updated from 8.5 to 9 and found one issue in mashup design page, the actual names like Widget, Layout, Explorer, Properties, Style Properties are not appearing in design mode.

Instead it shows label like "tw.mashup-builder.editor.category.label", "tw.mashup-builder.editor.placeholder.filters.widget" etc. Can anyone please help me on this?

I have attached the screenshot for reference. Did I missed anything while migration?

Thanks