log4net RollingFileAppender unexpectedly overwrites rollover files after a restart of the application

Question

We have an application with the following log4net configuration (v 2.0.12):

<appender name="LogFileAppenderXML" type="log4net.Appender.RollingFileAppender">
    <file value="D:\Logs\" />
    <datePattern value="yyyy-MM-dd'_AppName.xml'" />
    <preserveLogFileNameExtension value="true" />
    <appendToFile value="true" />
    <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
    <rollingStyle value="Composite" />
    <maxSizeRollBackups value="30" />
    <maximumFileSize value="500KB" /> <-- in production this value is much larger; 500KB produces rolled-over files faster when reproducing this behavior
    <staticLogFileName value="false" />
    <layout type="log4net.Layout.XmlLayout"/>
</appender>

This means we want to roll over both by date (day) and by size (i.e. rollingStyle=Composite). We also want to keep the filename of the logfile being actively logged to fixed (staticLogFileName) so that we can keep the file open with a viewer (Log4View). Everything works as expected within a single run of the application. But if I restart the application, the already rolled-over files are overwritten.

Assume the following files are already on the destination directory:

- 2021-07-22_AppName.xml
- 2021-07-22_AppName.1.xml
- 2021-07-22_AppName.2.xml
- 2021-07-22_AppName.3.xml

If I start the application, new log entries will be correctly appended to the main file 2021-07-22_AppName.xml. However, once the size in maximumFileSize is reached, data will be written to 2021-07-22_AppName.1.xml, thus overwriting existing data contained therein.

My expectation would be that the framework recognizes this initial state and 1) appends to the main file, and 2) chooses a filename that continues the rollover sequence (4 in this case).

What have I tried?

Based on this answer, I tried the following

    <file type="log4net.Util.PatternString" value="D:\\Logs\\.xml" />
    <datePattern value="yyyy-MM-dd'_AppName'" />

Also tried a conversionPattern like

    <file type="log4net.Util.PatternString">
        <conversionPattern value="D:\Logs\%date{yyyy-MM-dd}_AppName.xml" />
    </file>

but it creates files with the date both at the beginning and the end (i.e. 2021-07-22_AppName2021-07-22.xml

I've already looked at this question (I don't have multiple processes/instances logging to the file).

Questions

1. Is what I'm trying to do even supported/possible? If so, what am I missing?
2. Is there a way to prepend the date to file.value or is it always added at the end of the filename right before the extension?