Some icon themes ignore icons provided by an application

I recently installed Ubuntu MATE 19.10 on a spare laptop, installed Homebank and copied my data file to the new installation. Everything appeared to work correctly except that when viewing an account the icons that represent payment types were replaced by an icon that resembled the French flag. This icon also appeared in the account ledgers.

I've attached a screenshot that shows this problem with the "Add transaction" dialog. No icon should actually appear at this point but payment type icons should appear on the drop-down.

The author of Homebank has advised:
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this should be a problem with MATE.
homebank icons is not part of any standard set and there is no reason to display a flag, except if MATE has a bug for missing icons

under linux, it is located into /usr/share/homebank/* subfolders
icons for payment mode are into: /usr/share/homebank/icons/hicolor/16x16/status
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After much testing today I've concluded that certain icon sets which are selected manually or automatically when a theme is selected seem to ignore icons supplied by applications such as Homebank.

Blue Submarine and TraditionlOk are example of these erroneous themes. Changing the icon set to Adwaita or Ubuntu Mono Light restores Homebank's payment type icons.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: ubuntu-mate-icon-themes 19.10.5
ProcVersionSignature: Ubuntu 5.2.0-15.16-generic 5.2.9
Uname: Linux 5.2.0-15-generic x86_64
ApportVersion: 2.20.11-0ubuntu7
Architecture: amd64
CurrentDesktop: MATE
Date: Mon Sep 2 12:41:44 2019
InstallationDate: Installed on 2019-08-28 (4 days ago)
InstallationMedia: Ubuntu-MATE 19.10 "Eoan Ermine" - Alpha amd64 (20190828)
PackageArchitecture: all
SourcePackage: ubuntu-mate-artwork
UpgradeStatus: No upgrade log present (probably fresh install)