bumpforceclose on lnd embedded node not working

[warioishere]

Describe the bug

A user with Zeus embedded node (lnd 0.18.3) was not able to bump his force close tx. The errors which appeared:

[ERR] SWPR: Initial broadcast failed: init fee function: fee rate delta is zero"

"bumping fee for existing input=8c7862ecc38f9ea943b4d1b4b72e6fcb870bb8f889bc5c5ff14d65de76d843b8:0, old params=startingFeeRate={false 0}, immediate=false, exclusive_group=953921994644455424, budget=0.00000330 BTC, deadline=none, new params=startingFeeRate={true 7500}, immediate=true, exclusive_group=none, budget=0.00000330 BTC, deadline=none"

Skipped input..: has budget=0.00000330 BTC, but the starting fee requires 0.00002100 BTC (feerate=30 sat/vb), size=70 vb**

Mainly the last error logs puts on some questions on me.
Why is Zeus LND just seeing the anchor as the budget? User said, he as enough onchain utxos on the wallet.

I checked through the code but I dont really understand as I am a coder, and I dont know much about lnd on mobile node with neutrino.

But what I know, the fc that he had, should be bumpable:

https://mempool.space/tx/8c7862ecc38f9ea943b4d1b4b72e6fcb870bb8f889bc5c5ff14d65de76d843b8#vout=0

It had 2sats/vbyte

Also some experienced noderunner friends said, there should be no problem bumping this fc with bumpforceclosefee command in lnd.

More upcoming questions:

• what sweepersettings is lnd embedded using?
  - Does lnd embedded on Zeus is using some external wallet?
• For the sweeper to work, lnd embedded should be online, to check the onchain fees. Is this actually done?
  - is the bumpforceclosefee from lnd actually supportet? I dont see any apicalls in the code that calls this function

Looking foward for some discussions, or maybe experiences from other Zeus Users with embedded node.

The error messages definitely originated from LND.

"Skipped input" suggests that the Sweeper rejected certain inputs, which likely resulted in the budget being too small.

Cheerio

Reproduce

bump FC tx with force command using the right anchor output

ZEUS version

v0.9.1

Node interface

Embedded LND

Network

Tor

Device

OnePlus 7

Device operating system

Android 14

Log output

No response