Text line: inability to delete or change the "Begin" text

GIT commit: 7fe2bd3 / Windows 10

1) "My First Score"
2) Select a measure -> add a Text line (with the default "VII")

First result: like this other issue: #122541: The simple line fail with offsets and hooks, the default vertical offset is bad (overlapping with the top line of the staff)

3) Right-click -> Line properties

4) Remove the "Begin" text (VII) -> Ok

Result: nothing happens

5) Repeat step #3, and change "VII" by eg "X" ->Ok

Result: nothing happens again

But:

6) Go in Line properties last time: tick "Hook" (begin)

Result: the "X" text appears (and the hook)

NB: the "End" text works (ie by adding a text) because there is already a hook.

But by deleting this hook -> Ok -> Line properties -> Add "End text" -> Ok

Result: nothing happens, as the "Begin" text previously described.