Loss of persistent data file

I have 4 charts each with a dedicated named persistent data store (Json File) .

as i am testing persistent variables i have been starting and stopping node red with node-red-stop/start cli commands Not forced shutdowns (yet) and one Json file repeatedly gets lost/emptied.

I have changed the buffer period to 1 hour as i am collecting samples hourly so worst case i loose 1 data set so i find it hard to believe i stopped node red during a file operation twice, and even so since it was stopped it would im sure close all open files before responding stopped..

could this be an indication my pi system sd card is on its way out?

I am going to create a new persistent store.file just in case plantec1.json is referenced by anything else (very doubtful)

I was getting a MaxListenersExceeded warning during startup.

(node:32514) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 nodes-started listeners added. Use emitter.setMaxListeners() to increase limit

tho that isnt appearing any more after a little node tidying i had a few debug and triggers all over.

the json file has been lost since the warnings stopped.. it emptied for at least the 3rd time this evening just before i started this post??

DOH! of course most of the losses this evening could be down to me restarting within the 1 hour buffer empty, but not the first loss of the evening, nor the loss of the 5-6days worth of data historically collected noticed yesterday.