I found the solution to the frequently reported problem of invoices not displaying on the Money > Invoices page. This often occurs when the package is updated from a legacy version of SI to ‘master_2019.2’ or similar.
The problem was resolved after I noticed the languages and locales of my statement, estimate and quote templates did not match the language and local (en_US in my case) of my invoice template in Settings > Inv Prefs:
Once all these templates had the same location and locale settings, the invoices displayed just fine on the Money > Invoices page.
There is no restriction on having multiple preferences with different language and currency codes. The one thing that can cause a problem is if the currency sign is input as a character rather than an html code for the character. The US dollar sign is an exception. If you view the help on the Invoice Preferences Currency sign field, it explains this. I’ve include screen shots of test the I performed testing this.