It finally completed scanning, and after manually restarting the server, it's now displaying the files.  My only comment so far is that there does not appear to be a "home" button.  The up button will only take you to the top of the category you're already in.  There seems to be no easy way to get back to the category selection page.  Possibly something you might want to add.

OK, I have tried updating to V3, and I'm not entirely sure it's working.  It has been scanning my directories for three straight days, and there is still "nothing in the database".  Is this normal?

I see no magazine or other categories to use.  Using the latest 2.1.5 version, the only categories available are comics, books, and raw files.

I just started using Ubooquity and it's still working its way through my collection.  Looking at the logs it appears that most (if not all) PDFs fail to be added.  Here's an example from the logs:

20191222 09:42:59 [Scanner thread] ERROR com.ubooquity.data.feeder.a - Failed to insert Z:\Vault\Books\Comics & Manga\Legend of Zelda\The Legend of Zelda - Majora's Mask & A Link to the Past [Eng TPB].pdf
java.lang.OutOfMemoryError: Java heap space
   at java.util.Arrays.copyOf(Unknown Source) ~[na:1.8.0_231]
   at java.io.ByteArrayOutputStream.grow(Unknown Source) ~[na:1.8.0_231]
   at java.io.ByteArrayOutputStream.ensureCapacity(Unknown Source) ~[na:1.8.0_231]
   at java.io.ByteArrayOutputStream.write(Unknown Source) ~[na:1.8.0_231]
   at org.apache.pdfbox.io.IOUtils.copy(IOUtils.java:68) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.io.IOUtils.toByteArray(IOUtils.java:50) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.pdmodel.encryption.SecurityHandler.decryptStream(SecurityHandler.java:449) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.pdfparser.COSParser.parseFileObject(COSParser.java:785) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.pdfparser.COSParser.parseObjectDynamically(COSParser.java:742) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.pdfparser.COSParser.parseObjectDynamically(COSParser.java:673) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.pdfparser.COSParser.parseDictObjects(COSParser.java:633) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.pdfparser.PDFParser.initialParse(PDFParser.java:241) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.pdfparser.PDFParser.parse(PDFParser.java:276) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.pdmodel.PDDocument.load(PDDocument.java:1000) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.pdmodel.PDDocument.load(PDDocument.java:956) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at org.apache.pdfbox.pdmodel.PDDocument.load(PDDocument.java:904) ~[pdfbox-2.0.6.jar.6729965043262619269.tmp:2.0.6]
   at com.ubooquity.fileformat.pdf.b.a(SourceFile:34) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.b.d.a(SourceFile:62) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.data.feeder.a.b(SourceFile:531) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.data.feeder.a.b(SourceFile:468) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.data.feeder.a.b(SourceFile:112) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.data.feeder.a$$Lambda$5/16085064.run(Unknown Source) ~[na:na]
   at java.lang.Thread.run(Unknown Source) ~[na:1.8.0_231]

Just wanted to share the PDF OOM errors I'm seeing. I doubt it will help, but it can't hurt.