Procedural Xenon Tank always has Default Capacity

[bdleitner]

Apologies for the double-post if improper, I realized after posting in the forum that maybe it should just be a bug report:

I've been noticing odd behavior before with the procedural xenon tank, like if I revert a launch the tank stays the same size but ends up nearly empty.

I'm using KSPIE (full mod list attached) and just starting to experiment with beamed power so I'm experimenting with warping ships into position just to check out my understanding of how things work before I go launch for real. With my latest craft I noticed that Kerbal Engineer was saying I'd have ~10k dV but then when I moved it into position I only had 91 dV! After some experimenting I was able to determine the following:

• In the VAB, the size of the tank is 1.25m diameter and 10m long. It has a capacity of 99664.6 units of Xenon
• The default size for the procedural xenon tank is 0.625m diameter and 0.3m long with a capacity of 747.5 units. The math for these two capacities is consistent.
• When I launch, the tank shows full, but with a capacity of only "748". Going into the save file it has both amount and maxAmount equal to 747.5
• If I revert to VAB, the tank is the same size but now has only 747.5 units of the 99664.6.
• If I launch again from there, the tank shows as having 5.61 of the 747.5 (the same ratio as 747.5/99664.6)
• Most bizarrely, editing the save file to change the amount and maxAmount values doesn't work. When the I save the changes to a new file I can confirm the 99664.6 values are there, but when I load the game it goes back to 747.5 and a new save has the 747.5 values. The 747.5 value is found nowhere else in the part (though it could be calculated from something else).
• I went to visit some other crafts that used procedural Xenon tanks, though not nearly as large and sure enough they all have the same "748" capacity. It's unclear if this has been the case all along or if it manifesting when the craft is loaded as happened with the above. My previous uses of procedural Xenon tanks were always just to get "a bunch" of dV, so the max capacity is not something I checked on, though I had noticed the odd reduction in starting values after reverting a flight (in which case I just used hyperedit to refill, but I don't remember if I've ever seen a capacity other than 747.5).

I'm not sure if this is caused by another mod interfering, or if there's a bug in the procedural xenon tank when computing capacity outside the VAB such that it always uses the default regardless of tank size.

I uploaded my mod list and KSP.log to this github repo.

My educated guess based on observed behavior would be that when a ship is loaded, the values for amount and maxAmount are recalculated but the capacity is just using the default and not taking the part size into account.

[siimav]

I would assume that resource amounts are handled by InterstellarFuelSwitch. Not at all familiar with that modstack and unless the issue can be replicated in a minimal stockalike install, there's pretty much 0 chance of anyone from PP maintainers investigating this.

[siimav]

However what you could try is installing an older version of PP, like 2.5.0.0.

[bdleitner]

Good idea to try that, so I tried v2.5.0.0 and reloaded the save with the "fixed" values, but the same thing happened. I filed an issue with KSPIE to see if they might know if there's a conflict with InterstellarFuelSwitch.