Why won’t my Victron charger enter float mode

The IP22 manual (Link) is a little bit vague on this point, but here’s what it says (page 10)

Mode Absorption Float Storage Recondition
Li-Ion 14.2V Disabled 13.5V Disabled

So there is no Float mode at all with Li-Ion mode set.

How long does it stay in Absorption mode before moving to Storage?

Adaptive absorption stage duration can vary between a minimum of 30 minutes, up to a maximum limit of 8 hours (or as configured) for a deeply discharged battery.

Alternatively, fixed absorption duration can be selected; fixed absorption duration is the automatic default when Li-ion mode is selected.

(page 8, emphasis mine)

There is also a mention of Absorption stage duration of 0.5 hours (page 16) but this was calculated for a 100Ah battery, and I’m not sure if this is just an example, or if the charger actually uses this algorithm?

I also have an IP22 with a 314Ah battery, and I noticed that Absorption stage lasts longer than 30 minutes, but less than 2 hours. I did not notice the actual time.

Bottom line: I think you would be fine with the Li-Ion preset, as long as you are patient and wait longer than 30 minutes for Storage mode.