Homepage is not cached and has no priority

Hi,
And first, thanks for this great plugin, which gives me amazing results!

I have a serious issue though on my website:

Homepage won’t be cached whatever the settings I try.
It actually keeps ending up at the last position in warmup table with no priority set (blank) every time cache is automatically regenerated (either time or action based).
And then I can’t even manually cache it (green check then when I refresh it’s black cross again).

The only way I can cache it is by refreshing the warmup table (homepage is then position one with priority 10) every day and manually cache the page!
Then, the day after, homepage is not cached any longer and is last position with no priority again ??

I don’t understand, maybe something is wrong with my settings?
I have excluded all post types except pages and posts, and no manual page or URL.

Can you help me please?