A minor annoyance, but —
1. With a file folder in Navigator selected and 4 open contact sheets, CMD+Q to shutdown PM+
2. Reopen PM+
3. In the Navigator, select the main pictures folder, and a list of sub folders appears. All of these sub folders have sub folders, but the normal triangle icon indicating their presence is missing. (See attached file)
4. Collapse the main picture folder and then re-open it.
5. The sub-folders reappear with the triangle icon to indicate the presence of sub-folders there.
My System
macOS Mojave Version 10.14.4
iMac Retina 5K, 27-inch 2017
Processor 4.2 GHz Intel Core i7
Memory 32 GB 2400 MHz DDR4
Graphics Radeon Pro 580 8 GB