Steps to reproduce

1. Split big .ics files of a old NC export (to workaround Importing bigger .ICS files only imports part of it #2570)
2. Start importing the first files, which runs fine
3. Notice that the importer doesn't list the desired calendar for the last two files anymore

I compared the files, but they look fine so far (VCALENDAR surrounding items, VEVENT and VTODO items). I also tried the first files, which looks good. Changing filename doesn't solve the issue. Reimporting the original big file, doesn't also work anymore. Logout and new session doesn't helped as well.

Expected behaviour

Like all the other files, I wan't to import it to the same calendar so far.

Actual behaviour

I can't pick the right (existing) calendar, to add more items to this calendar.
(no browser console messages appear, explaining why the item is removed from the list)

Calendar app

Calendar app version: 2.0.4

CalDAV-clients used: -

Client configuration

Browser: Firefox 80

Operating system: Linux Mint 20

Server configuration

Operating system: CentOS

Web server: Nginx

Database: MariaDB

PHP version: (e.g. 7.0.3)

Nextcloud Version: 19.0.2

Updated from an older installed version or fresh install: fresh