I would be 99.9% certain that it isnāt a glitch/bug, but rather something specific to the setup in your App. This is such a core piece of functionality that if it didnāt work reliably we would all know about it and would be hounding Glide to get it fixed, please trust me on that.
I also wouldnāt mind betting that if you publish your App and test it as an actual user signing in using an actual, real, valid email address - it will work perfectly.
There is nothing āunsafeā about using row owners, so please donāt use that as a reason to create a separate App. Of course, there can be all sorts of reasons why it can make sense to create a separate App, but concerns over Row Owners not working shouldnāt be one of them.