Sumatra opening new documents in new instance despite settings

[denniskhk]

SumatraPDF version

• Version [18454, pre-release]

Describe the bug
Settings set to Use Tabs - checked in Advance Options as well (UseTabs = true). However, opening additional PDF files would cause the files to be opened in new instances of Sumatra instead of new tabs. This only started happening after upgrading to latest pre-release.

To Reproduce
Steps to reproduce the behavior:

1. Open a PDF file
2. Open another/more PDF file(s)

Expected behavior
With Settings set to Use Tabs, new PDF files should open in new tabs, not new instances

File that reproduces the problem
n/a

Additional context
Was using pre-releases before this but this bug only started appearing in latest pre-release. Uninstalled and reinstalled, same problem. Uninstalled and reverted to stable release, problem disappeared.

[GitHubRulesOK]

Think this has been mentioned before and thus must be a changed default !
it has always been a comment of mine ensure "both tabs and reuse-instance true" to ensure expected behaviours, thus on install those should have been correct defaults !
3.61 installed ReuseInstance = true
Pr-Rel installed ReuseInstance = true
Thus there should be no difference
"works for me"