Thank you to try Ancestris.
Did you install Ancestris version 10 or version 11 ?
How many individuals do you have in your GEDCOM file ?
By default, Ancestris uses 1Gb of memory. This could be not enough for big GEDCOM files.
Ancestris loads the entire file in memory, it is one of its limits.
When the program freezes, this implies usually that the memory used is too low.
If you uses a 64b Java installation, you can add more memory to the program in the preferences. Do it before open a GEDCOM file.
I can't tell you why Apple makes Ancestris disappear.
Perhaps it is a new function of Apple who uninstall unapproved application when a crash is implied.
You can launch Ancestris from the Ancestris/bin directory, launch in a console the script "ancestris"
Please read our documentation to recreate a launcher and an icon in the dock :
https://docs.ancestris.org/books/user-guide/page/step-by-step-installation-on-macos#bkmrk-docking-ancestris-inZurga