while not strictly necessary you may want to add
followTail = 1
to your inputs.conf to ignore the older data which may be causing the issue.
from the doc:
followTail =1
Can be used to force splunk to skip past all current data for a given stanza.
* In more detail: this is intended to mean that if you start up splunk with a
stanza configured this way, all data in the file at the time it is first
encountered will not be read. Only data arriving after that first
encounter time will be read.
* This can be used to "skip over" data from old log files, or old portions of
log files, to get started on current data right away
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