Tie replaced with dotted note. But why?

Hello Forum,

I new to musescore and I'm kind of stuck. I'm trying to create a lead sheet for Nica's Dream and right in the second measure my tie is getting replaced with a dotted note. But why? Am I missing something? What am I doing wrong? (On a side note: I'm in 4/4 and shouldn't a dotted whole note possible at all?)

Here's what I did:

1. Select pickup measure
2. Press "n" to go into "note-entry mode"
3. Typed "f" for the first note
4. Type "7" to select whole notes
5. Type "c" the insert second note
6. Click the "Half note" button
7. Click the "Tie" button

I'm using:
OS: macOS 10.16, Arch.: x86_64, MuseScore version (64-bit): 3.6.2.548020600, revision: 3224f34

Many thanks in advance.

-Sebastian