Not to worry, but all our Themes have been converted to Collections. This why you are not able to see Themes. We have now introduced a new concept called Collections which are pre-set video templates which has various layouts. There are a wide array of options for you to choose from.
To access the Collections, press on the '+' icon in your workspace. From this, you can either choose from the list of collections available or choose a 'Blank Template'. You can also click on 'See all' to gain access to all the pre-set templates