can you post (attach !) the MT meteotemplateLive.txt from the .../template directory after the MB posts (it contains your MB posted data)!?
Also, can you post (a) picture(s) of the MT database schema !?
as @davidefa has shown, something is fishy ....
MT will only accept data via the API for existing database fields - and the PPx fields are in the extra table.
When the PP4-PP6 markers are not contained in the meteotemplateLive.txt file, even though they have been posted by MB, maybe the API doesn't identify them as fields to be filled and archived.

Have you switched off the standard MB posting for Meteotemplate in "Weather Nets" ? - put  "upload interval" to "no upload" and save (!!)
If you have two parallel posts, the API might get a hickup.

Extract from your ( meteotemplate ) cache/apiLog.txt:
2022-05-18 13:29:15
INFOS:
Authorized access.
Current date/time: 2022-05-18 13:29:15
api called by http
update U: 1652873354
update SW: meteobridge
update T: 25.9
update TMX: 25.9
update TMN: 25.9
update H: 48
update P: 1022.3
update W: 6.1
update G: 7.9
update B: 230
update R: 0.0
update RR: 0.0
update S: 821.0
update UV: 5.1
update TIN: 24.1
update HIN: 50
update TS1: 46.5
update TS2: 30.8
update TS3: 20.7
update TS4: 37.2
update SM1: 0.0
update SM2: 0.0
update SM3: 0.0
update SM4: 0.0
update SM5: 0.0
update SM6: 0.0
update LW1: 0.0
update LT1: 46.5
update LW2: 0.0
update LT2: 30.8
update PP3: 5.1
update PP2: 8.4
update PP1: 9.1
Begin of common part of api script
Start handling live data
Checking if extra sensors should be logged
Extra sensors data to save in db: TIN, HIN, UV, ET, TS1, LW1, LT1, SM1, PP1, TS2, LW2, LT2, SM2, PP2, TS3, SM3, PP3, TS4, SM4, SM5, SM6
add live data: D: 14
add live data: DTime: 1652873344
add live data: A: 26.3
add live data: ATime: 1652873344
calculated D: 14
calculated A: 26
Save meteotemplateLive.txt: {"U":1652873354,"SW":"meteobridge","T":25.9,"TMX":25.9,"TMN":25.9,"H":48,"P":1022.3,"W":6.1,"G":7.9,"B":230,"R":0,"RR":0,"S":821,"UV":5.1,"TIN":24.1,"HIN":50,"TS1":46.5,"TS2":30.8,"TS3":20.7,"TS4":37.2,"SM1":0,"SM2":0,"SM3":0,"SM4":0,"SM5":0,"SM6":0,"LW1":0,"LT1":46.5,"LW2":0,"LT2":30.8,"PP3":5.1,"PP2":8.4,"PP1":9.1,"UTime":1652873355,"SWTime":1652873355,"TTime":1652873355,"TMXTime":1652873355,"TMNTime":1652873355,"HTime":1652873355,"PTime":1652873355,"WTime":1652873355,"GTime":1652873355,"BTime":1652873355,"RTime":1652873355,"RRTime":1652873355,"STime":1652873355,"UVTime":1652873355,"TINTime":1652873355,"HINTime":1652873355,"TS1Time":1652873355,"TS2Time":1652873355,"TS3Time":1652873355,"TS4Time":1652873355,"SM1Time":1652873355,"SM2Time":1652873355,"SM3Time":1652873355,"SM4Time":1652873355,"SM5Time":1652873355,"SM6Time":1652873355,"LW1Time":1652873355,"LT1Time":1652873355,"LW2Time":1652873355,"LT2Time":1652873355,"PP3Time":1652873355,"PP2Time":1652873355,"PP1Time":1652873355,"D":14,"DTime":1652873355,"A":26,"ATime":1652873355}

The first part with the list of:
update SSS: XXXis the list of the parameters passed to api.php ( you can pass any parameter for example if you pass: &MIKEY=MOUSE youll find a row 'update MIKEY: MOUSE' )
from this list I can see there is no PP4, PP5, PP6

For a further check you can use the 'ear' tool ( from olicat ) this will show you what your meteobridge is sending
Simply direct your meteobridge upload to the ear tool

NOTE
When making these tests ( changing the fields sent to the api.php script ) you should/could delete the meteotemplateLive.txt file, not to get confused ( by new and 'stale' values/fields ).
I mean that even if you send a field only once ( the MIKEY=MOUSE in the above example ) the meteotemplateLive.txt file will contein this field for 30 minutes ( then it will be removed ).
This is, I think, to  overcome the wireless sensors 'hiccups' that may happen.
These 'stale' fields are distinguished in the cache/apiLog.txt file as:
add live data: MIKEY: MOUSE

You guys are lucky we here in the UK pay about £1.60 a litre for unleaded (in a supermarket) and around £1.75+ a litre for diesel! That's about $1.99 and $2.17 litre prices respectively.

Stuart

As far as I'm concerned, this thread has become irrelevant. Time to act.

Headline today is over 6 dollars in places.

Our average is equal too over 6 USD.