External drive's files not showing, but I know it has been half-filled with data. It works fine on Ubuntu but not on macOS?
On extra checking macos should be able to Read ntfs but not write. But this solution should still work

If you have removed paragon then you have removed the programs that can convert binary data on the disk into something macos understands. Thus you need something like paragon for macos to read it  

Now Ubuntu includes the programs to convert the binary data to something Linux can read. So gives a possible solution. 

I think the solutions are


restore from a backup not under ntfs eg from you cloud backup. You should always have something like that if you use a Computer  
Use paragon or something like that to read the data. 
Boot into Ubuntu or Windows and copy the data to another drive formatted in a way that Linux or Windows and macos can read  I think that has to be exFat. Copy the data onto this drive. Or copy to a network file server  or cloud based server. Then reboot into macos and copy the data from the exfat partition.