Fix strange behaviour in ribbon plot

[athowes]

ISO3	Issues?
BWA	None
CMR	Missing direct in {3, 4} 25-29
KEN	Missing direct in {3, 4}
LSO	None
MOZ	Missing direct in {3, 4}
MWI	None
NAM	None
SWZ	Missing direct in {3, 4}
TZA	None
UGA	Weird spikes, missing direct in {3, 4} 25-29
ZAF	Missing direct in {3, 4} 25-29
ZMB	Missing direct in {3, 4} 25-29
ZWE	None

[athowes]

(One of) the missing categories is really empty. Probably can be traced back to something in the high risk differentiation script.

[athowes]

Need to put shapes for partially raw, then fix UGA bumps, then it's done. :v:

[athowes]

Just the UGA bumps left to finish this.

[athowes]

UGA bumps are not just an artefact -- goes deeper (either data issue or model issue, though if model why only here?)

[athowes]

This is gone in the most recent version of the fit. Don't know what the issue was.